Proof that Mitt Romney suffers from double Romnesia comes with an easy-to-miss detail that he insisted on in his official portrait from his one term as governor of Massachusetts.

At first, the 52- by 37-inch oil painting seems distinct from the portraits of the commonwealth’s other governors, mainly in the inclusion of a picture within a picture of his wife, something not done by any of his 69 predecessors.

On closer look, there is something else, what appears to be a leather-bound document on the desk along with the framed picture of Ann Romney. The cover is embossed with a gold symbol that might escape notice.

This winged staff entwined with two serpents is the caduceus, and it was the only thing Romney explicitly asked to have included other than his wife. That’s because the caduceus is associated with medicine, and Romney wanted it somewhere in the portrait to represent the landmark Massachusetts health-care bill he signed into law in 2006.

“He wanted to the symbol there because to him, that was his great achievement as governor,” recalls the 66-year-old artist, Richard Whitney.

The inclusion of the Caduceus seemed no less important to Romney than the inclusion of his wife. But the symbol was the greater challenge to the painting’s composition.

“The whole problem was what to do with the caduceus,” Whitney recalls. “I tried the symbol in a frame on the other side of him, I tried a wall above ... It didn’t seem to work.”

Inspiration came when Romney and Whitney paid a Sunday visit to the governor’s office, now occupied by Deval Patrick. They chanced to see a leather folder used to hold legislation being signed into law.

Whitney proposed including such a folder in the painting with a gold caduceus added to the front as if it were a ceremonial copy of the historic health-care bill. Romney agreed.

“Mitt said as long as he can recognize that symbol if we put it on the cover of the bill; if he can recognize that symbol, he will know it’s in the portrait,” Whitney recalls.

The remaining question was how to incorporate the folder into the painting. Romney picked up the real one to try various possibilities.

“We pretended that was his health-care bill, and he played around with that, whether he held it or put it on a table,” Whitney says.

They finally decided that it would be set by the framed photo of Romney’s wife, which created a problem of another kind after Whitney submitted a sketch to the art committee that oversees the official portraits. The committee objected to Romney including his wife’s image.

“In no way shape or manner am I allowed to have his wife’s portrait in the painting,” Whitney says. “It was never done before.”

Romney’s reaction was immediate.

“Mitt got on the phone to the art committee and he told them, ‘I’m paying for this portrait. I’m going to have what I want in this portrait, and that’s that,’” Whitney recalls.

Whitney later noted: “I was very impressed with that. He was adamant his wife’s picture had to be in his portrait somewhere.”

And it was not just any picture. Romney gave Whitney a copy of his favorite photo of his wife so it could be reproduced in the portrait. Whitney was happy to do so, though her bright white smile presented a complication because her husband’s smile is at least as pearly.

“If he’s smiling, it’s going to be too much,” Whiney says. “An advertisement for toothpaste.”

So, Romney got just a closed-mouth start of a smile in the portrait, which now had the added effect of making him look less like a politician trying to get your vote than a governor who has achieved something. And that accomplishment was sitting right there on the desk with a golden caduceus gleaming on the cover.

Romney was smiling as brightly as the caduceus when the painting was officially unveiled at the statehouse in July 2009. He got a rousing welcome from former colleagues of both major parties.

“The most applause I’ve heard since the day I announced I wasn’t running for a second term,” he joked.

He got a big laugh and went for another.

“One thing this painting has in common with real life is that in the painting my hair doesn’t move either.”

He declared Whitney “a wonderful artist” and said he hoped to commission other paintings of his family. A reporter asked if perhaps a presidential portrait was in the future. Romney managed to maintain his smile even though he had lost a bid to become the Republican nominee the year before.

“Not very likely,” he said.

That same month Romney wrote an op-ed piece for USA Today urging the new president to follow his bipartisan example in passing federal health-care reform. President Obama was seeking to do just that, using Romney’s historic bill as a blueprint, even eliciting the help of such former Romney health-care advisers as MIT professor Jonathan Gruber.

“They’re the same f--king bill,” Gruber was later quoted saying.

The Machiavellian money guys who manipulate the Republican right then sought to portray Obama’s health-care bill as a socialistic, big-government invasion of a every true, hardworking American’s individual rights. The bill also presented a handy way to oppose Obama for a reason other than his race.

More reasons presented themselves as Obama continued the struggle to revive the economy after the near collapse he inherited from his predecessor. Obama sank so low in the polls that Romney decided he might have a shot at getting a presidential portrait after all.

But Romney’s landmark health-care bill was indeed so close to Obamacare as to make him suspect among conservatives. Had Romney’s body in the portrait not been as immobile as his hair, he no doubt would have scooted over to cover that folder with the golden caduceus.

He did seek the political equivalent, developing Romnesia about what had been his proudest achievement. The man who had been so determined to remember his wife in his portrait now disavowed the bill that he had been equally insistent on including. The onetime champion of Romneycare declared that if elected president he would repeal Obamacare.

All of which was confusing to the artist whose preparations for the portrait included cutting out a Photoshopped picture of a caduceus, then taping it to the front of a folder to serve as a model for the immortalized bill.

“I don’t understand it,” Whitney says. “He was the first person in the country to do something about health care, long before Obama or anybody else. That’s a great achievement.”

The importance of health-care reform became all the more apparent to Whitney and his wife, fellow self-employed artist Sandy Sherman, after their health-insurance company more than doubled their premium and then moved out of their home state of New Hampshire.

Whitney had just become old enough to qualify for Medicare, but his wife was still six months shy. They could only hope nothing happened before she was eligible.

“We held our breath,” Whitney says.

Meanwhile, Romnesia became so pervasive that the only constants between the former Romney and the present one beyond his wife were that he is white and that he has an intimate relationship with money.

But then a videotape surfaced in which Romney could be heard writing off 47 percent of Americans. He arrived at the first presidential debate with polls showing he needed to appear more caring. He proceeded to give a surprise demonstration of double Romnesia, acting in the debate as if he had never sought to make others forget his achievements in Massachusetts.

Romney even forgot that he had forgotten the bill with the golden caduceus. Obama was as stunned as if that other Romney in the portrait had come to life and appeared before him.

By the second debate, Obama seemed to have recovered himself. He got a big laugh of his own during a campaign appearance in Virginia on Friday, when he introduced the term “Romnesia.”

“The good news: Obamacare covers preexisting conditions,” Obama said.

And of course so does Romneycare.