Do I require both a Runtime and SQL User CAL for each user?

Currently we are running two SQL based applications (Separate physical boxes), a CRM and an Accounting application, the CRM is a SQL 2008 Standard Ed (64-bit) and the Accounting is a SQL 2005 Standard Ed. (32-bit). The CRM issues SQL Runtime CALs, and we purchase User CALs for all the Accounting Software users. The question is if a user has a SQL User CAL already do they require the Runtime CAL.

We currently purchase both the Runtime and SQL User CALs for every user as 99% of the time they use both, roughly 25 users.

My understanding is that the SQL User CAL grants the user access to multiple servers running SQL so the User CAL should be sufficient.