Enhanced Xeno Farm and Intensive Farming are both unlocked by Xeno Farm Construction II (was playing as the humans, but no idea if that's even relevant). Enhanced Xeno provides 3 food (description is still the DA one from Xeno and says five; Basic appears to have been converted to Xeno and downsized, but that's not the issue, though a correct description would be nice) and has 1 maintenance, while Intensive provides 6 food...and has 1 maintenance.
So, to sum up, one tech is unlocking two improvements, one of which obsoletes the other one.
TA 0.95b.002 (beta 4a)