So I have a question here regarding ally and or villain packs that come with more than one unit (such as hera syndulla and c1-10p) do they count as one joint ally in a campaign for the rebels?

no, i think the only card that allows two allies , is the ' Counterparts ' card

though, you could house rule it to add them, and use the new allie rules from the tyrants of Lothal

They are different groups with their own deployment cards.

The advantage is that the mission that they come with usually gives you access to both deployment cards. So while you're still limited to taking one ally, you have more options.