organic chemistry - Protonation of compounds with two or three neighboring nitrogens

I am working with organic compounds. Many of them are similar to this ones:

The R group (which I paste for completeness) is:

I am a bit confused about the protonation state of those amine-compounds at pH=7.4, in aqueous solution.

N-substitued amines are more basic than the other ones. For example methylamine is more basic than ammonia. But the protonation state of the ring is more complex than that, and I can't understand how to protonate it.

I suppose that in a kind of analogy with the guanidine (product) we could protonate again the double bonded nitrogen (imine).

Will amine be protonated? Will that compound has $+2$ charge?

Guanidine

It will possibly be protonated in the double bounded nitrogen, because it has more negative density charge and resonation is not broken. Any other point of view will be welcome.