they don't would mine two blocks it's a non sense.
Probably they found two solutions (both invalid!)
No. Miners cannot find two solutions without running two processes (i.e. two pools). Neither of the blocks were invalid, they simply were not built upon by other miners so those blocks became stale (orphaned).
franky1's answer is the most likely answer for this situation.
This is my speculation as well, but even if only one of those blocks were orphaned/staled, they just lost a full block, $10k+ for having poor communication between their own nodes.