php 5.5, pdo_pgsql, opcache, class name already in use

I've compiled php 5.5 with pdo_pgsql both statically and shared. The
problem occurs when I have 5.5 code that uses a class from another
namespace whose class name already exists in the current namespace.
The class in the current namespace is not being used by the class that
is trying to use the other namespace class instead.

If I then have two vhosts, with the same code (different directories),
when pdo_pgsql is compiled as a shared object, then only one of the
vhosts will work (the one that received the first web request).
Compiling pdo_pgsql statically and also disabling opcache results is
both vhosts not working. In all three cases, it seems to be the same
problem, php errors out stating that class name is already in use.

This is happening on RHEL 6.5. I've been able to compile it on RHEL
5.6 and did not see the problem there.


Has anybody experienced similar problems? Any suggestions on what to check?



-- 
Greg