Italian to English Law/Patents Law: Patents, Trademarks, Copyright clinical trials

This word is used in a sentence near the end of an agreement to conduct a clinical drug trial.

I'm confused about this word in relation to the word "firmato":

"Il presente atto viene *firmato* dalle parti contraenti e **sottoscritto** per consenso dal Responsabile dello studio."

I find that both "firmato" and "sottoscrito" can be translated as "signed". And in this context, I don't think that the other meanings of "sottoscrivere" (underwrite, subscribe) apply.

I think that they may mean that the director of the study "countersigns" the document ... but that would be "controfirmare," no?

There must be a reason that they are using the two separate words -- firmato and sottoscritto -- here. Please help me understand what they mean by "sottoscritto".

Grazie dell'aiuto!