In People v Bernell (2010 NY Slip Op 02346 [4th Dept 3/23/10]) the Fourth Department vacated a consecutive sentences when the sentencing court mistakenly believed that it could not impose concurrent sentences:

At sentencing, defendant requested that the sentence run concurrently with the indeterminate sentence he was serving at that time. In denying the request, County Court stated that it was "not authorized by law to make that concurrent. It must be consecutive . . . ." In fact, however, the court had the discretion to impose concurrent sentences... " The failure of the court to apprehend the extent of its discretion deprived defendant of the right to be sentenced as provided by law' " (People v Schafer, 19 AD3d 1133). We therefore modify the judgment by vacating the sentence, and we remit the matter to County Court for resentencing.