Yes, we preserve unique identifiers for all taxonomy objects (term groups, term sets, and terms).
There are exceptions:
- Migrating a taxonomy object within the same term store.
- An object with the same ID at the destination.
- SharePoint 2010 (not supported on this version).
Exceptions are due to the fact that a single term store cannot have more than one object with the same unique identifier. This is only possible when migrating from a term store to a separate term store on the same environment (since they are different term stores).
If Sharegate hits any of these exceptions, it will generate a new ID and show a warning.
There will be no warning for SharePoint 2010 since it is not supported at all.