This message occurs when LINGO imports a non-native file converting it to a LINGO model.  Non-native file formats (e.g., MPS, MPI and/or LP) allow for variable and row names that aren’t entirely compatible with LINGO’s syntax (e.g., spaces in names).  In order to overcome this, LINGO will patch these names by replacing inadmissible characters in the names with underscores and truncating names longer than 64 characters.  This can create problems because two or more unique MPS names may get mapped into one LINGO name.  A technique for avoiding this problem is to use R/C naming conventions.  Refer to the Use R/C format names for MPS I/O option for more information.