Are you using net-snmp for this, or a built-in snmp agent? If you're using net-snmp, what version? Are they the same on both servers?
Built-in, I am guessing. Thought there were all net-snmp. Whatever came with OSX. Versions 5.4.2.1 on 10.6.x and 5.6 - on 10.7.
We have 40-50 xServes deployed and about 15 2006-2010 Mac Pro edit bays. Those on Mavericks are fine, anything below 10.8 - a coin toss - may or may not display CPU/mem. The one that doesn't even display volumes - 10.6.4 on xServe 3,1. Can't upgrade it to Mavericks because of legacy app compatibility.
Usually in Windows, Linux and (in my limited experience) OSX worlds, when you have the same app installed on several systems, you could compared timestamps and content of key folders to try and see why an app would misbehave. Not the case with net-snmp?