RIMM Memory Upgrade

I have a Dell here that the user wants to add more RAM to his machine. He currently has 128mb of RIMM. I opened the case and saw that there are only two slots for memory chips. One contains the RIMM chip. The other contains a sort of “dummy” chip. There are no memory modules on this chip although there are contacts on the bottom and very few circuit traces. Is this a dummy chip ie. spaceholder or is this needed and his machine is not upgradeable? I haven’t seen that type of chip before and thisis my first experience with RIMM. Can someone steer me in the right direction? I appreciate it.