[Tagging] Bug when importing tag with same value

[bradenmacdonald]

There is a bug if we try to import tags over a taxonomy that share the same Tag Value.

It can be reproduced importing the Template Taxonomy over the "Lightcast Open Skills Taxonomy".
Both taxonomies have a tag with the value "piano". In the plan, it tries to create the tag piano for the Template before deleting the one from Lightcast, raising an error.