It wouldn't. Only one will ID the barrel maker. The other could be an inspector mark, date mark, proof code, etc..
They are REALLY rare, but if it has a large 1,2,3,4, or 5 on the stock it is for sure a prototype. If it has a number over 6 with just numbers and no letters, it may be. Look at some pictures of M1 carbine stocks, and see if it looks any different. If it has any weird stamps on the wood, re-ask the question with a description of the stamp.
The link leads one to conclude that there could be roughly a half million different stamps.
That it was stamped six times. The significance of the stamps themselves depends on what the stamps are.
22 stamps
There are many different groupings of stamps: An album A stamp collection A stamp exhibit A sheet of stamps - a complete sheet as issued by the post office A pane of stamps - A booklet page A block of stamps - multiples that are still attached A pair of stamps - Two connected, often used with coil stamps A strip of stamps - More than two connected coil stamps
If you have four 25 stamps and three 30 stamps altogether it would by worth 190.
Clear stamps are transparent when purchased whilst regular stamps are opaque and clear stamps are not normally sold in sheets as they are sold individually.
They have date code stamps on the barrel which can be looked up on the manufacture date link on the Remington Society of America.
There are several different places where a person can purchase alphabet stamps. Stores such as Target, Walmart, Kmart, and arts and craft stores all sell alphabet stamps.
No, stamps on letters can be quite different, they differ in two main ways, the value of the stamp, each value may be a different colour and/or design, and the country producing the stamps will have it's own unique design from others countries.
One can find reliable information about different kinds of post office stamps by visiting a local post office where one will all sorts of stamps and other items like envelops.
Please see the link below for examples of Tiffany & Co.'s hallmark stamps.