Freddie Quell : Freddie from Frederick meaning Peaceful Ruler; Quell to vanquish, suppress, subdue.
Lancaster Dodd : Lancaster from Lune (Pure) +ceaster (castra, Latin for camp). Dodd means “Of the people” and is related to the Germanic word for rounded and therefore “dull”. Perhaps invoking dodder which means to quake, tremble. Perhaps also a pun on “dad/god”.
Peggy Dodd : Peggy is a nickname of Margaret which means Pearl. Peggy is used to invoke “pegged” (she’s pregnant the first half of the film) or perhaps the expression a “round peg” in square hole. Also, L. Ron Hubbard’s first wife was named Margaret “Polly” Grubb.
Doris Solstad Day : Doris from Dorian an ancient mode of music, related to the Greek word for Gift (doron). Her maiden name Solstad means Sun City in Norwegian. Obviously Doris Day invokes the actress, but it was also the name of the wife of George “Bud” Day, a highly decorated U.S. soldier (Doris Sorenson Day).
Winn Manchester : Winn short for Winnie short for Winifred (“win Freddie?”), the anglicized form of Gwenfrewi, which means Blessed Peace. Manchester from Mam (breast, breast like hill) +ceaster (castra, Latin for camp).
See also : The Meaning of the Names in Inception.