The next time Don Jr publicly expresses other than total agreement with his Dad will be the first time he does. (And that’s fine by me, he’s a loyal son who undoubtedly often agrees with Trump.)
In this case, Jr was first. He's been in the pro-Vance camp for quite a while now and has been working on convincing his father to officially endorse.
I find it fascinating that the entire political world deeply cares who Trump Sr endorses while going into snits about the particular choices. (Not addressing you, Lurker, just a general observation.)