If there was a crumb on the table and you cut it in half, would you
have two crumbs or two halves of a crumb?

If you leave them together for 9 months and they produce some further
crumbs then you can declare with certainty that you did have two
crumbs.

It may sound crumby but this is the only positive test known to science.

http://www.crumbmuseum.com/

You?d still have one crumb but two half tables -- unless the crumb got
cut at the same time.