Five counterfelt $20 bills, made by taping together, pieces of cut-up $10's and $20's, have been received by Harvard Square merchants, Cambridge police announced Tuesday.

The culprits have been pasting the outside margin of a $20-bill to the inside of a $10, Lt. Det. Alfred E. Marckini said. Then they tape in the face from the $20 in the oval in the center.

One of the counterfeits was detected, when a merchant noticed Andrew Jackson's face, which usually appears on a $20, pasted on a $10 bill.

The "remodeled" currency is made about one-quarter inch shorter than normal bills, Marckini said, so that the counterfeiters can make 12 bills out of 10.