Discarding conflicting packet due to recent request

[khouzam yaghi]

i am receiving this error from time to time in the radius log

Error: Discarding conflicting packet from client PPPOE1 port 33184 - ID: 1
due to recent request

i searched online and found very old posts about this error, what does it
mean? is it something related to the database slow? or broken NAS? my NAS
is a Linux server running accel-ppp as a pppoe-server.
is this something related to the NAS itself or to my configuration with
freeradius? also what does this error means?

Regards.