I just found out that it is not possible to track several model targets at the same time. In my Unity project we have a big problem that we have over 2000 models which need AR content. It is too much work to edit every single one. So the idea was to split them up in 4 different components (e.g. arms, legs, body, head), each of them with different variations (long body, short body, ...). The idea was just to download the necessary parts (e.g. short arms, long legs, round body and red head) and make each of them so a single model target.
Now that this is not possible, I need a different solution. Since every part is always at the same position I asked myself if it is possible to download several 3D-Models (+AR-Content) and merge them to one big Model Target.
Thanks for your help and I am also happy for any other ideas.