The Umi-Clones are the evil clones of Team Umizoomi. (They'll appear in an upcoming special)
Overtime, the Troublemakers have been making a special machine to make evil clones of Team Umizoomi. They manage to collect DNA and used it to make the clones. However, the machine had a flaw and couldn't copy the clones to look exactly like the team. Luckily, this makes it to tell the Umi-Clones and Team Umizoomi apart.