Although the writers probably put them in the same scene to appeal to the brony fandom, there is a logical reason for the two appearing alongside Rarity in Sweetie Belle's dream: she dreams of being a singer, and her getting the wrong cutie mark is obviously a horrible thought. Maybe her distressed mind made up a worst-case scenario, where she got the wrong cutie mark while performing in front of the three people she looks the most up to? Vinyl and Tavi are probably two of the more well-known musicians in Equestria, what with Tavi playing her cello during the GGG and Vinyl being the DJ in Cadance's wedding, so it'd make sense if they were her idols.



Bah, theory time over, I like your artstyle, it's very cute!