Correlation-based watermark detection inherently assumes that a pseudo-random watermark pattern is present in the cover signal at a given location. However, disparity-coherent watermarks for stereo video content are broken into pieces which are offset one with respect to the others. Acoustic transmission yields echoes due to multi-path propagation and may thus introduce watermark replicates in the recorded audio track. In such cases, the watermark energy is not concentrated in a single element of the cross-correlation array but rather distributed over a number of them. As a result, it is necessary to devise aggregation strategies to recover these scattered watermarks. In this paper, we present a method that relies on outlier detection to identify which elements of the correlation array are associated to the embedded watermark and should be aggregated. Experimental results clearly demonstrate the ability of this technique to recover the watermark without introducing undesired false positives, even in noisy conditions.