These seven long-legged beetles floated on the top when I soaked my home-grown broad beans prior to sowing yesterday. Unfortunately they died overnight in the damp pot I kept them in.
I looked at all the beans but could only find this one with a hole in it.
On the internet it explains that they don’t spoil the seed as the larvae only eat the cotyledons, which are not needed for germination or growth. 

Bruchus rufimanus   –    (possibly.)    RHS website.
I’ve tried to preserve the beetles and the seed in 50% gin with water.