I found a glitch I'm not sure how it starts happening but if I make lets say a mithril large hammer head and then I put say a copper ingot in the slot in the anvil on the side with the spike I can make a mithril large hammer head when I hammer it.
sorry for the lack of info on how it happens I only just noticed it today.
I am running alpha 0.0.7
and my specs are windows 7 ultimate 64bit, Intel i5 processor and a 9600 gt