Import xer updates the project calendars though import option is set to 'Keep existing'

Hi,

In Primavera 15 R2,  say we have Project A with project calendar 'Cal'

Export this project to xer file.

then make some changes to 'Cal' in the Project A.

Now import the xer file and in the import option project data-Calendars 'keep existing' and update the existing project Project A in the import.

We expect that te Cal should not be updated, however it is updating..

Is this the case from the previous versions as well..?

Thanks

Parthi