I acquired this as part of a lot a cover that I really wanted. While I have not as yet collected these, I have enjoyed looking at them and reading about them.
In typical fashion the Scott catalog says that later on the 2-cent stamp was sold for one cent, but doesn't say why what 2 cent and 1 cent stamps paid for initially.
15L14 (1¢) Bronze on cover tied by acid with nice hand-stamp as well.
15L17 (2¢) Bronze on cover tied by acid (with writing on the inside).
The writing on the inside looks like an order for some materials, but it is tough to read. It is addressed to a "varnish manufacturer". This second cover/letter is dated August 8, 1849.