This excerpt from a Keith Olbermann SCD column sheds some light on the 1974 Padres situation but doesn't answer why only some cards showed Washington:
"This was the season Topps jumped the gun on the planned move of the San Diego Padres, and issued the 14 lower-numbered Padres (and the No. 599 rookie card featuring Padre Dave Freisleben) in two varieties: San Diego or “Washington, Nat’l Lea.” The proof cards of the Padres up to number 387 all list the team correctly (no “Washington” proof has ever been found), but the color scheme for the lettering is all different. Instead of black on a brownish orange, they’re all white on brown – not a mistake as such, but a design change (and paralleled by other aesthetic changes for other teams as well).
The proof cards, as ever, give considerable insight to baseball card history. The Topps Vault auctioned a 1974 proof sheet on eBay in 2003, and all the Padres players on it are listed with San Diego – and are thus covered by the hand-markings of the set editor, insisting that they be changed to Washington. Just to further clarify what was happening at Topps HQ, this proof sheet is, as most were, dated – marked “Dec. 6, 1973” – and thus indicating what kind of chaos had enveloped the card company less than three months before the cards were due in stores".
- See more at:
http://www.sportscollectorsdigest.co....ph9GvKzt.dpuf