Salaah

Musaafir muqtadi making the intention of four rakaats behind a musaafir imaam

Q:

1. If during traveling, an Imaam makes intention of qasr Asr but the muqtadi, who is also a traveler, mistakenly made intention of four rakaats. Will the muqtadi need to repeat the salaah (two rakaats qasr) or the niyyat of Imaam will be the one to supersede over that of the muqtadi and the muqtadi’s salaah behind the Imaam will be valid?

2. As a muqtadi, since I was not sure of the above, I repeated the Asr and prayed two rakaat qasr, was this action, in cases of doubts, correct until I come to know the right maslah?