No, not directly.
Assuming you really want to do it for Beyond earth and have not just chosen the wrong forum, the most elegant workaround I can think of:
- Give the unit a Unit_BuildingClassRequireds-Prereq.
- Then you create a dummy building that has no Tech requirement and a cost of -1 (which means it can't be constructed and won't show up in the UI, other than the Civilopedia) as well as a ConquestProbability to 0.
- Add a free PlayerPerk to the other Tech via Technology_FreePlayerPerks.
- Make that PlayerPerk grant the free FreeBuilding. (Note that this requires the buildingCLASS, not a building type -> <FreeBuilding>BUILDINGCLASS_RELIC</FreeBuilding>)
That way, you have the unit show up on one technology, and on the other Technology you can use the PlayerPerk to add a Note via the Help-Tag.
If instead you meant to post in the Civ5 forums, the easiest way to do it would be via lua. Use
City.CanTrain() and check for both technologies.