Can a challenger initiate the challenge for breaking rule X, and then change and say the profile is challenged for breaking rule Y?
I’m not sure if you are asking regarding (1) challenge reasons (incorrect submission, duplicate, deceased, fake) or regarding (2) what aspect of a submission is incorrect.
(1) Not exactly. First, the dispute (let’s say about a profile being a duplicate) has to be ruled and executed. If the submitter wins, the challenge period is extended so that other reasons can be used to challenge the profile. If it were not like this, a malicious submitter could challenge themself with a wrong reason and get away with it.
(2) If a profile is challenged for being allegedly incorrect, jurors have to decide wether it’s incorrect or not independently of the evidence that the challenger or the submitter presented. See for example what is going on with case 652.