I do apologize if this is in fact a duplicate, but I did try searching for the issue, and no matches came up, also, I have yet to hear of this on any of the normal lines of game discussion. (Reddit, MC forums, twitter, etc) so I figured I'd submit in case this is a new bug.

When placing two tools in the crafting table (tested with bows only, and those were sourced from slain skeletons) to repair the item, the two damaged items are not being consumed, Instead allowing for infinite duplication of a finished repair. (Note the actual levels of repair are not effected, i.e. two almost broken bows (85-90% damaged) will still return a bow that is 75-65% used. But using this bug one could very quickly attain a fully repaired bow.)

-HAS NOT been tested on armor or other tools (enchanted or other wise), and in the anvils UI.
-THIS DOES occur in both the 2x2 grid and 3x3 grid.
-This DOES NOT affect normal crafting operations such as making tools, or items like doors stairs, etc.

I also had my game open to LAN, if that helps.

Thank you and again, sorry if this is a duplicate.