If you have more than one individual therapist, I don't feel that is a good idea. I had an online one I acquired when my regular in-person therapist was away and when she returned, it was awkward having two because one can't be split that way and get therapy to work. My T asked me to get rid of the online one and I did and did not regret it, despite the difficulty and embarrassment in "getting rid of" that T.

If your T's are for different types of therapy, I have had no trouble talking to one about the other but the one I'm talking to won't comment much since it's not their area of expertise. It's not any harder than talking to a therapist about your psychiatrist, or, in my case, my therapist about my group therapists. Therapy is about using sessions and the people in them to help ourselves so I don't know that venting to one therapist about the other helps anything? We need to address the person with whom we have the problem about the problem, not other people, the other people can't do anything for us, it's a different relationship.