Yes you can. But there are some terms and condition which is you have to follow.
In ThemeForest there are 2 types of authors. First one is Exclusive Authors and second one is Non Exclusive authors.
An Exclusive Author can’t sale same item to other marketplace and that was why they are getting more than Non Exclusive Authors.
But a Non Exclusive Author can sale an item to other marketplace and that was why there commission rate will be same. Whereas an Exclusive Author will get more day by day by increasing their sales volume. For more you can check this Click Here.