Hello, just received these unsevered reply cards from an auction and from what I can tell they are UY7 - PM4+PR4 and UY12a - PM6+PR6 worth 1.50 and 12.00 respectively. The book explanations were a little confusing and I'm not too familiar with these to begin with :-) thanks for your help in confirming or denying!
The 1c green George/Martha card is UY7 printed from vertically curved steel plates with separation 1 or printed from horizontally curved plates with separation 2, or 3, or 4. Papers for UY7 include cream, numerous shades of buff, off white, and canary. The 3c red McKinley was printed on cream or on buff and with 8 different separations is UY12. Your UY12 appears to be separated by printer's rules which limits it to separation 5, 5a, 6, 7, or 8. UY12 is on buff and UY12a is on yellow (sorry but I can't determine paper color from pix).