I just checked purchases from that IP, and not only do those two share the same IP and similar user/character/minion names, there are many other characters on the same IP with similar names. Here's a sampling from the purchase log:
Kirbzz (Kirbzz) 67.170.235.121 buy A Whip ($26) 7:38 PM EST
Kirbz (Kirbyzx) 67.170.235.121 sell A Buckler ($878) 6:10 PM EST
Rawr (Rawrz) 67.170.235.121 buy A Rapier ($270) March 24 2005 8:51 PM EST
LOLKeyzisON (Kirbyzz) 67.170.235.121 buy A Rapier ($270) March 24 2005 8:18 PM EST
Keyz (Kirbzx) 67.170.235.121 buy A Rapier ($42) March 23 2005 10:54 PM EST
sharingankirby (Keyz) 67.170.235.121 buy A Cutlass ($81) March 23 2005 9:58 PM EST
kirbymixmasta (Roies) 67.170.235.121 sell 510 Rounded Pebbles