When I was combining pickle files from multiple repeats I encountered following error. I was using different topology files which has same number of atoms from two different repeats(eg: pipe1.pdb, pipe2.pdb with same number of lipid and protein residue).
~/basicrta1.1_combine_trj/pipeB$ python -m basicrta.combine --contacts contacts1B_7.0.pkl contacts2B_7.0.pkl --output combinedB_contacts_7.0.pkl
Combining 2 contact files...
Loading file 1/2: contacts1B_7.0.pkl
Loading file 2/2: contacts2B_7.0.pkl
Validating file compatibility...
ERROR: Incompatible ag2 residues between file 0 and file 1