The scheme was yet another blemish for Facebook as Mr. Zuckerberg starts the first of two days of testimony before Congress. Legislators are expected to grill him about the company’s role in a series of scandals, including a toxic bloom of fake news during the 2016 election and the harvesting of data from up to 87 million Facebook users by Cambridge Analytica, a political consulting firm connected to President Trump’s campaign.

Last week, in the run-up to Mr. Zuckerberg’s testimony, Facebook announced new measures requiring those who manage pages with large followings and pages related to political candidates and issues to verify their identities. The requirement is meant to give users more information about such pages, including any previous names they may have had.

“This will make it much harder for people to administer a page using a fake account, which is strictly against our policies,” the company said in a blog post on April 6.

Patrisse Cullors, a founder of the Black Lives Matter movement, wrote in a post on Twitter on Monday that she and her supporters had asked Facebook “over and over again” to shut down the fraudulent Black Lives Matter page, but that Facebook had balked at doing so.

“These fake BLM accounts and fake BLM people literally stealing money off Black Death is so stomach churning I can’t even begin to explain,” she wrote. “Glad it’s down now.”

Black Lives Matter activists said in a statement that they regretted that “so many people were deceived by the recent high profile scam” and had made gifts and donations that the movement did not receive.

“We live in a digital world, and it’s extremely important that platforms like Facebook and Twitter do their due diligence with users so that supporters of our movement, and movements like ours, aren’t misled and that resources aren’t misappropriated,” the statement said.