We have two separate Episerver forms with submit button on the page. When we click the first form submit button, it's doing validations and shows error messages without doing any page postback. When we click on the second Episerver form submit button, the entire page is refreshed. 

Episerver forms hierarchy first form appears at the top and is followed by the second form.

If we swap those forms also the first form validates within the block without doing page postback.

Is there any limitation for the second submit button on the page?

The expectation is that the second submission should work without refreshing the page (it should validate within the block)