> If my J1 research is expired then I return home, can I get another
> J1 clinical visa within the first 2 years??
If you J1 research DOESN'T have a HRR, you can switch to a different visa H1, F1, O1 without a problem.
If you returned, and applied for a clinical J1 lets say a couple of months later, I don't know whether they would require you to go through the 'change in J1 category routine' I mentioned before.