I run Proliant 800's, HP Vectra's, and Intergraph dual Pentium Pro 200's with no problem at all.
As in the previous post, both processors must be installed prior to the e-smith install. There may be something in your bios that may affect the OS seing both processors. If there is a setting related to OS type, you may want to play with it. Either way, if you just added the 2nd processor, you will have to re-install.
Once properly installed, LILO will by default boot up in multiprocessor mode, yet give you a choice to boot up in single processor mode at startup (LILO UP, where UP=uni-processor).
Chaloner Hale