Chris,
first: gammacon.UDT is derived from core UDT, but uses its own table structure (as any module with modified structures should do). There is a crossgrade script available, if you want to use gammacon.UDT and keep your data from core module 3.0.x/3.1.x
second: thanks for pointing out missing references in gammacon.UDT, we will have a look at it and publish an update ASAP.
third: but this should not be your problem. Do you use Database Owner other than DBO or object qualifier?
Try to remove the module from all tabs, clear the recycle bin, delete gammacon.UDT, check the tables ModuleDefinitions, TabModuleDefinitions, ModuleSettings and TabModuleSettings for possible leftovers, also the gammacon tables should be removed. Re-install the module and check for install errors. If everything is ok, add the module to a page.
Please contact me directly, if there are still issues.