Hi, this is a bit of an esoteric issue I just stumbled over, but I'd like to flag this up anyhow. For some reason (most likely boneheaded error on my side) I wound up with duplicate resids for two ion-atoms: TER HETATM 9325 CL CL S 1 10.578 23.153 35.662 1.00 75.71 Cl1- HETATM 9326 CL CL S 2 -6.546 32.210 31.507 1.00 80.31 Cl1- HETATM 9327 CL CL S 3 21.899 28.037 25.883 1.00 86.22 Cl1- HETATM 9328 K K S 3 7.259 -0.149 19.530 1.00 91.09 K1+ TER Phenix (1.9-1692) seemingly happily accepted the input and proceeded with refinement and validation. After upgrading my coot installation to the latest build the error was flagged. I think this sort of mistake should have at least been flagged in the validation stage or is this out of scope for phenix? Cheers, Carsten