Those are just figures that someone assembled from the parts you identified (that's a yellowed Steel Brigade torso on your second figure and Sonic Fighters Dial Tone parts, though).
I'd like to believe it were that simple. These were not picked up from some collector or at a convention where customs might be the norm. These were part of a childhood collection. I doubt that they were taken apart and reassembled. I didn't even find loose body parts in the bin that would verify these were just part swaps.