Need help!

I maintained a dial-up ISP. I'm new to this company and I'm not the one who setup the server. With all 4 freeradius server, one has a problem. It has double logs in mysql. Meaning two different RadAcctId but with the same AcctSessionId. Is there anyone could help me distinguish why it has double record in mysql when in radius logs,it has one request only.

Here is the sample:

| RadAcctId | AcctSessionId | UserName |
| 517069 | 3C001FC0 | foo |
| 517071 | 3C001FC0 | foo |
| 517075 | 3C001FC0 | foo |

Server has 192MB memory and running in 300Mhz processor with kernel version 2.4.

I already upgrade to the latest freeradius version but still no luck. Anyone already experienced this kind of problem?