Manship 5 and 6 has two different descriptions for the two '70s presses. From 6:
"Very rare 1975 1st. press 2 turn deadwax EC 5709 A @ 6 O'Clock, upside down circled BA @ 12 O'Clock position. bottom of the label text credits arranger: Fred Cagaanan note: The E in the matrix resembles a back-to-front 3"
"original 1976 press. This press has a 2 turn 16.41mm wide deadwax. Scratched matrix reads EC 5709 A @ 6 o'clock,upside down circled BA @ 12 o'clock position. Note: label does NOT credit arranger: Fred Cagaanan."
although it's not clear, reading the two descriptions, they sound like the same plates as Chalky says -- nothing contradicts at least. If they are the same plates they are the same mix and only the label credit differentiates the presses.