kart driver
Note that there are currently 5 different Cup2s in the stock front size (245/35-19) and 7 different Cup2s in the stock rear size (265/35-19). Two of the front sizes are homologated for BMW motorsport and Tirerack calls out one of those as "Star BMW M2". There has just been a 2nd BMW * tire released notated as "BMW * DT1".
Similarly in the rear there are now three Cup2s that are BMW *, the original plus DT and DT1 versions.
The USA Michelin site isn't useful to view all of these, and since you're in the EU, you can view the sizes and versions
on the UK site or pick the site for Germany - they have the same listings.
More than likely these are all similar enough that mixability (front to rear compatibility in terms of peak grip and in terms of transient response, i.e. slip angle versus grip force) would not be an issue. However, it wouldn't hurt to match the front and rear versions. I would tend to stay away from the MO (Mercedes) and N0 (Porsche) specific versions.