I've always wondered how credit for scientific discoveries is attributed. Take this example from Wikipedia:
The Merkle–Damgård construction was described in Ralph Merkle's Ph.D. thesis in 1979. Ralph Merkle and Ivan Damgård independently proved [...]
Ivan Bjerre Damgård [...] discovered the structure independently of Ralph Merkle and published it in 1989.
Here we have 2 researchers who independently discovered the same structure. One of them published it in 1979. The other published it a whole 10 years later. Why is it that the credit is not attributed to the person who discovered it first?