Audio encoder for encoding a two-channel audio signal, comprising: a time-spectrum converter for converting the two-channel audio signal into a spectral representation; a spectral analyzer for providing an indication of a first set of first spectral portions to be encoded with a first spectral resolution and of a second set of second spectral portions to be encoded with a second spectral resolution, the second spectral resolution being smaller than the first spectral resolution, the second set of second spectral portions representing reconstruction bands; a two-channel analyzer for analyzing the second spectral portions of the second set of second spectral portions of the two-channel audio signal within the reconstruction band to determine a two-channel identification for each second spectral portion of the second set of second spectral portions either identifying a first two-channel representation or a second two-channel representation to obtain the two-channel identifications for the second spectral portions of the second set of second spectral portions; a core encoder for encoding the first set of first spectral portions to provide a first encoded representation; and a parameter calculator for calculating parametric data on the second set of second spectral portions using the two-channel identifications as determined by the two-channel analyzer to obtain an encoded parametric representation, wherein an encoded two-channel audio signal comprises the first encoded representation, the encoded parametric representation and the two-channel identifications for the second spectral portions of the second set of second spectral portions. a time-spectrum converter for converting the two-channel audio signal into a spectral representation; a spectral analyzer for providing an indication of a first set of first spectral portions to be encoded with a first spectral resolution and of a second set of second spectral portions to be encoded with a second spectral resolution, the second spectral resolution being smaller than the first spectral resolution, the second set of second spectral portions representing reconstruction bands; a two-channel analyzer for analyzing the second spectral portions of the second set of second spectral portions of the two-channel audio signal within the reconstruction band to determine a two-channel identification for each second spectral portion of the second set of second spectral portions either identifying a first two-channel representation or a second two-channel representation to obtain the two-channel identifications for the second spectral portions of the second set of second spectral portions; a core encoder for encoding the first set of first spectral portions to provide a first encoded representation; and a parameter calculator for calculating parametric data on the second set of second spectral portions using the two-channel identifications as determined by the two-channel analyzer to obtain an encoded parametric representation, wherein an encoded two-channel audio signal comprises the first encoded representation, the encoded parametric representation and the two-channel identifications for the second spectral portions of the second set of second spectral portions. <EOS>