Receiving duplicate packets on prp link

Ubuntu release: Ubuntu 20.04 (Ubuntu 20.04.3 LTS)
Package version: 5.10.0

After setting the same mac address on enp4s0 as enp3s0, I set up the prp link with the command

ip link add name prp0 type hsr slave1 enp3s0 slave2 enp4s0 version 1 proto 1

I made a simple udp client that sends packets every 10 ms containing an int that increments for each packet. The udp client was running on computer 1.

I made a simple udp server that receives the packets and prints the containing int. The udp server was running on computer 2.

The computers were connected directly to each other with two network cables.

The expected result was that the udp server would not receive any duplicates.

What happened was that the first 1821 packets were ok. After that 55% of the packets were duplicates.'

After a reboot, the first packets were ok, but again, duplicates started appearing after some time.

I got more or less the same results with version 0 of prp.