I can't find any difference between the NXP '1G74 vs. '2G74 datasheets either, but the TI corresponding datasheets show some differencies. E g TI '1G74 is only specified at 3.3 and 5V for -40 to +125, and for some packages not recommended at all for that temp range.
My guess is that NXP supplies the '1G74 as a 2nd source for TI. TI and NXP have had some sort of mutual "2nd source agreement" on std logic; however I don't now if that't the case anymore.
The LVC/ALVC nomenclature is a bit confusing since some parts' '1Gxx refers to "1st generation" while other refers to "single gate" (and '2Gxx to "2nd generation" and "dual gate", respectively).