Fish and Wildlife, which administers the duck stamp program, printed about 3.5 million stamps attached to cards with the wrong number.

Instead of the correct number, which was 1-800-782-6724, the misprint advises callers to dial 1-800-872-6724. The first spells out 1-800-STAMP24. The second spells 1-800-TRAMP24.

The agency said it would cost too much to reprint them at a steep $300,000.

“That’s a lot of money we can be using for wildlife conservation. With all of the needs for conservation, it doesn’t make sense to divert money away from an important cause,” spokeswoman Rachel Levin said.