Maybe they want to prove they are better in general and that's why decide to mirror you (as the fight is fair as in even matchup). So if they do win, apparently that would be proof for them they are better. I think this is the logic behind people mirror matching you. Or they want to get you salty by trying to beat you with your own character.
Free Step Dodge
KING JAIMY
KING JAIMY
And Jann Lee is top tier in lag, so yeah... xD. But I think you have experienced that already. 
tokiopewpew
I hate mirror matches soooo much^^
And yeah, I can't help it, but online, Jann Lee always beats me out on R1F both on mid and jab. However, I like playing against him. Guessing game after dragon gunner catches me is always fun in some way.
And yeah, I can't help it, but online, Jann Lee always beats me out on R1F both on mid and jab. However, I like playing against him. Guessing game after dragon gunner catches me is always fun in some way.
Force_of_Nature
Mirror matches are so Lol. I always laughed when someone would pick Ayane against me then they try to abuse online tactics.