Try these strings
Test String, Result
1) aBabAb, aaAbbB
2) aaAaAaaAA, aaaaaAAAA
3) aaAabAaaAA, aaaaaAAAAb
4) aaAaBAaaAA, BaaaaaAAAA
5) aBCabcAb, BaaAbcCb
6) aAAabBBbAaaA, aaAAAAbBBaab
7) ABCDEFGHIJKLMNOPQRSTUVWXYZijklmnopqrstuvwxyz, ABCDEFGHIJKLMNOPQRSTUVWXYZijklmnopqrstuvwxyz
If gets worse...