what is the compliment referred to(during the conversation of song between amiens and jaques) in the scene 5th of act 2nd..why is it compared to the encounter of two dog-apes...?

Jaques compares two men complimenting each other with two baboons together. Jaques means that he feels kind of like a beggar when he is complimented and "I have given him a penny and he renders me the beggarly thanks."

but why 'complimenting each other' is compared to the encounter of two

dog-apes..?

I think the comparison alludes to the two men not being that smart engaging in empty compliments. That's my take.