Updates on Bidirectional Transactional Replication

I have successfully set up a platform with Bidirectional Transaction Replication working between 2 servers. However, updates do not seem to work if both servers simultaneously has the same field updated.

For example executing the following SQL continuously on both servers will not add up to the correct number of updates.

update table1 set field1 = field1 + 1

I have reduced the polling interval down to 1 second but this does not solve the problem.

I assume there is a solution as I assume this will happen with all updates on the same data. Does anyone know the answer?

P.S. I have set loopback detection to true.