Back when there was 4.5.0 and 4.5.1 some of the patches could be applied to either version and essentially bring them up to the same levels. I suspect the system you are dealing with was base 4.5.0 and then patched to G2 (incremental 2). There were no sql updates in place that changed the alamode version entry from 4.5.0 to 4.5.1.
You can manually update that single db entry and then AUA will proceed.
update alamode set str_val = '4.5.1' where type = 'VERSION';