OC: OpenComputers_MC1.7.10_1.7.5.1290_universal
MC: 1.7.10

By default villagers ignore metadata. So u could trade with them by using different items for example:
Charcoal instead of coal,
broken tools,
etc.
Component trading doesn't ignore metadata.
I think its a defect and should be fixed in the next release.
The main reason why it is so important.