Usage of 'only' with a verb

They only stamp academic documents versus they stamp academic document only: which one is correct and what are the implications of the non-correct form?

(Context: university office that does other businesses but also stamps academic documents.)

Solution 1:

Based on the context you give, I think what you're looking for is:

They stamp only academic documents.

i.e. they do a variety of other things, but as far as stamping goes, it's limited to academic documents.

The first example you gave implies that they don't do anything besides stamping academic documents.

The second example is more ambiguous and could mean either—I would avoid using a construction like that.

Solution 2:

Both are correct and convey the same meanings. However, the first one, "They only stamp academic documents," sounds better, as the word that "only" is modifying ("stamp") is closer.

I'm confused by the context you mention, though. This sentence says that there is a university office which does not stamp other businesses - they only stamp academic documents. That's the opposite of what you said in the "context" part.