Nope, they aren't pseudonyms...

Willy Rickmer Rickmers, Victor von Richter, and Oliver Onions (yes, pronounced just like the vegetable).

Willy Rickmers was an explorer (and son of shipbuilder Rickmer Clasen Rickmers); von Richter was a chemist; and Oliver Onions was born (the same year as Rickmers) George Oliver Onions -- a commercial artist who later became a prolific writer publishing under his middle and surname (even after legally changing his name to George Oliver in his mid-40's).  A long-lived fellow, he died in his late 80's, in 1961, but his wife, fellow author Berta Ruck, won the race, dying at age 100 in 1978.