Is a Peace dollar with ALP instead of the mint mark special?

Yes, but not in a valuable way. "ALP" is an counterstamp indicating the coin is a replica made of a metal alloy variously known as alpaca silver, nickel silver, or German silver.

Despite its names this alloy doesn't contain any silver. Proportions vary depending on what it's being used for but it's normally about half copper with the rest being nickel, zinc, and sometimes tin.

As such the coin's metal value is only a few cents, and it has no numismatic value because it's a copy.