**Summary** When replica exchange is enabled in the lambda-only mode, all reference temperatures `ref-t` are the same among replicas. However, the log tells that another branch `temperature+lambda` is used. ```text Replica exchange in temperature and lambda state 298.1 298.1 298.1 298.1 0 1 2 3 ``` **GROMACS version** 2021, 2022, etc. **Steps to reproduce** Suppose there are 4 simulation replicas with the MDP option snippet as below: ```text ; Temperature coupling tcoupl = V-rescale ref-t = 298.1 ; Values are the same in other MDP option files ; Free energy control stuff free_energy = yes init_lambda_state = 0 ; Values in other MDP option files can be 1,2,3 ``` Then, launch multiple simulations with the following command: ```bash gmx mdrun -multidir 0 1 2 3 -replex 200 ... ``` **What is the current bug behavior?** The log tells that another branch `temperature+lambda` is used. ```text Replica exchange in temperature and lambda state 298.1 298.1 298.1 298.1 0 1 2 3 ``` **What did you expect the correct behavior to be?** Here are the log that we expect: ```text Replica exchange in lambda state 0 1 2 3 ``` **Possible fixes** Fix comparison of float numbers in function repl_quantity.