LTI and Moodle

Hello All,

We have two campuses that are using two different Moodle instances.  They both have a Practical Nursing program, and therefore both access a 3rd Party content provider through a LTI External Tool.  The two Moodle sites are under the same domain.  The LTI tool is not differentiating between the two sub domains when students access the resource with the same generated $Userid #'s.

Example:

Moodle instances are subs of main domain: 

• domain.com/pn
• domain.com/spn

Student 1: testuser1@domain.com Moodle Site 1 generated $Userid=116 

Student 2: testuser2@doamin.com Moodle Site 2 generated $Userid=116

• Student 1 accesses the External tool First:  Has access granted and shows their username in external portal.
• Student 2 accesses the External tool Second:  Access is granted, but shows Student 1's username in external portal.
• Any work completed by Student 2 in the external site is recorded on Student 1's grades

My question is:  Is there any way to configure the tool or Moodle to differentiate between the two students even though they have the same Moodle generated $Userid #'s?  Maybe in the custom parameters of the tool?  I know I have read that the $Userid is the key to the database is Moodle, and that you should not try to change it, so looking for other solutions to this issue.

Thanks in advance for any help!