Technically, these are slang terms. If you have to put more than one prefix on a word, then you don't know the appropriate term for what you're trying to describe.
For example, antidisestablishment means "against the removal of establishment", disestablishment meaning the removal of establishment, anti a prefix meaning to be against something; you could simply say pro-establishment. Unpremeditated means "not planned ahead of time", premeditated meaning with forethought and/or planning, and un a prefix used to refer to an opposing state or nature (such as unfair, or uncaring); so you could simply say accidental or spontaneously.
There isn't really a specific term for a dual prefix because there is no need for a dual prefix, mainly because a dual prefix will almost always be a double-negative, or at the very least, simply describe another, less complicated word.
I sincerely hope this helps.