Possible ACLR cache corruption on SQLServer

In certain condition the ACLR cache of a user can be invalid.
But Invalid in a safe way, the user will not see content that it is allowed to see on search results.

This happens in the following case:

• a user U1 set an ACL on a document and generate a new read ACL (ACLR A)
• someone change the ACL on the previous document, the ACLR A is still present in the ACLR table
• another user U2 log in and performs some NXQL that initialize its ACLR cache
• someone set an ACL and generate again ACLR A, that already exists on the ACLR table
• the ACLR cache for the user U2 is not updated with the ACLR A because there is no insert in the ACLR table