[gmx-users] Error using -demux flag in trjcat (development version)

[Robert Johnson]

Hello everyone,
I recently ran a replica exchange calculation using the development
version of Gromacs. I used the demux.pl script to generate the two
.xvg files. I am trying to feed the replica_index.xvg file to trjcat,
but I'm getting a strange error message that I don't understand. Here
is the command and error message:

trjcat -f traj[0-9]{,[0-9]}.xtc -demux replica_index.xvg


Program trjcat, VERSION 3.3.99_development_20060330
Source code file: gmx_trjcat.c, line: 296

Fatal error:
Demuxing the same replica 1 twice at time 2.400000

An excerpt of the index_replica.xvg file is shown below. I'm saving
coordinates and attempting replica exchange swaps every 0.6 ps. Does
anyone know what this error message means and how I fix it?
Thanks,
Bob Johnson

0           0    1    2    3    4    5    6    7    8    9   10   11
12   13   14   15   16   17   18   19   20   21   22   23   24   25
26   27   28   29   30   31   32   33   34   35   36   37   38   39
40   41   42   43   44   45   46   47   48   49   50   51   52   53
54   55   56   57   58   59   60   61   62   63
0.6         1    0    3    2    4    5    6    7    9    8   10   11
12   13   14   15   16   17   18   19   20   21   22   23   24   25
26   27   28   29   30   31   32   33   35   34   37   36   38   39
40   41   42   43   44   45   46   47   49   48   50   51   53   52
54   55   56   57   58   59   61   60   62   63
1.2         1    0    3    2    4    5    6    7    9    8   10   11
12   13   14   15   16   17   18   19   20   22   21   24   23   25
26   27   28   29   30   31   32   33   35   34   37   38   36   39
40   41   42   43   44   45   46   49   47   48   50   53   51   52
54   56   55   57   58   59   61   60   62   63
1.8         1    0    3    2    4    5    6    7    8    9   10   11
12   13   14   15   16   17   19   18   20   22   21   24   23   25
26   27   28   29   30   31   32   33   35   34   37   38   39   36
40   41   43   42   44   45   46   49   48   47   50   53   52   51
54   56   57   55   58   59   61   60   63   62
2.4         1    0    3    2    4    5    6    7    8    9   10   11
12   13   14   15   16   17   19   18   20   21   22   24   23   25
26   28   27   29   30   32   31   35   33   34   37   38   39   36
40   43   41   44   42   46   45   48   49   50   47   53   52   51
54   56   57   58   55   61   59   60   63   62