Multiple high-pass and compression or just one?

Just looking for advice here.

I have a bunch of vocals all bussed into one "vocals" aux track. Let's say there's six of them. Each one of them has a high-pass filter and light compression on it.

Now what I'd like to know is what the effect of summing these is in regards to these processes. My guess for compression is that it's somewhat obviously double compressing the final result. As for the high-pass though, I don't really know.

Does applying a high-pass (low-cut, whatevs) to each signal do anything if I'm applying an identical high-pass to the final summed aux track?

I've been turning this over in my head for a day or two and don't have any insight beyond "it's probably unnecessary to high-pass each track initially". But I would like to know if anyone has any insight on this.

Compression I can understand in so far as I might want different settings for different styles, but hypothetically would one final compression do the same as six initial (and assuming identical) compressions?

This might all be a bit too nitty gritty to matter too, I realize. Geekin out perhaps.