double major Greek/ Latin?

That sounds challenging, but fascinating! I've only studied Latin, but it's very interesting to see how these languages have grown into the modern languages of our world. If you have a passion for it, then do it.

Are you talking about Ancient or contemporary Greek?

Studying Classics, I do both Latin and Ancient Greek. Both languages are far from simple, but it remains entirely feasible as long as you have a good head for languages, and for grammar in particular. Both languages are far more complex grammatically than western languages (I have little to no knowledge of the grammatical systems of non indo-european languages), and a much greater morphological paradigm to learn (word endings, that is). It doesn't help that while the two languages are quite similar, there is sufficient difference between the two as well as extra complication within each separate language that beyond the basic principles you cannot really use either as a means to learn the other.

I don't want to put you off. Both languages are genuinely interesting to study, and with the level of preserved texts undoubtedly rewarding. Would it be hard? Quite probably, of that I will not deceive you. That does not however mean that it can't be enjoyable at the same time.

I am currently studying Greek, and have studied Latin for about 2 years at the same time

Depending on how easy you learn any language, I'd say it's very possible

I managed quite well (but quit at Latin 'cause I didn't like it)

If you want to, just do it!!

Well a complete waste of time and effort learning Latin.. who are you going to speak it with? The pope?

It's a dead language so please don't be drawn into the "fascinating" side of it as you can't use it.