i've noticed IE send duplicate requests

I;ve noticed that 1 out of every 1000 requests, IE will send the same exact request to the server twice. same time same header info, everything. (From the same user)

IE is always a source of surprise.

I think that two identical calls produce no real side-effects.
If both enter into the critical section (inside lock method),
one overwrite the other, but it is not a matter, because params are the same.

Actually, lock methods I wrote had no monitor/barrier mechanism to serialize access and there is the possibility that two calls from different users, for the same resource, at the same time, will produce a result than is not "really right".

In a collaborative environment, such as that I wrote the class for, it is not a real problem because a subseguent call of status will advice one of contenders that he/she has lost (the lock). The loser probably has to choose another task.

In a scenario like a e-commerce site, this is not acceptable and there is the need to add a monitor to the lock method. It is very simple to add a check if the resource is still free inside the transaction of MDB2 driver (or of any db driver).