This can be a problem if there are two laboratories in KeyLAB which have the same sample prefix.
KeyLAB will recognise that the sample IDs are duplicated. The problems can be caused by having two laboratories which have the same sample prefix. If there are some projects in one laboratory and some on the other the samples will be incremented using the same sample prefix. This can be the cause of the duplicated sample IDs.
To solve the problem check if there are two laboratories in KeyLAB with the same sample prefix. Change the sample prefix for one laboratory (so they dont match). The sample ID increments will reset for the changed prefix.
If it's not the laboratory please contact support.