Loki has shown that you can have variants of yourself that look like you (the main Hiddleston "Loki" there is a variant, and so was the "President Loki"), and variants that don't (see lady Loki, Gator Loki, Kid Loki, that black Loki, etc). We only saw a few versions of Stephen Strange in MoM, there is probably more of him.Heroes in different universes look different (NWH).
Now they don't (MOM).
Peggy taking the super-soldier serum shows one crazy alternate reality across the sprawling multiverse (What If).
Now apparently there's lots of Peggy Caps (MOM).
Figure it out FFS, lol.
Wanda would probably be more consistent across the multiverse because she's supposed to be a Nexus being.
I don't know why multiple Captain Carters is an issue though? They showed one in "What If?", there are probably more of her given how new realities branch out from small things based on the What If premise.