Time Travel Clone
Use of time travel causes the same character to exist at at least 2 points in space simultaneously.
for simplicity lets call the characters clones. Sometimes a clone might not be allowed to see another clone in order to prevent a time paradox (although that could just be the characters simply being careful). In Dexter's Laboratory dexter and his 3 clones (who are different ages) team up to beat mandark, who also has 3 clones. I have also seen this trope in Redvs Blue blood gulch cronicles church had quite a few clones, one of them had a different color for some reason.
Hello, Unknown Troper. You'll need to get known to lend a hand here.