We derive new uniqueness results for pLr, Lr, 1q-type block-term decompositions of third-order tensors by drawing connections to sparse component analysis (SCA). It is shown that our uniqueness results have a natural application in the context of the blind source separation problem, since they ensure uniqueness even amongst pLr, Lr, 1q-decompositions with incomparable rank profiles, allowing for stronger separation results for signals consisting of sums of exponentials in the presence of common poles among the source signals. As a byproduct, this line of ideas also suggests a new approach for computing pLr, Lr, 1q-decompositions, which proceeds by sequentially computing a canonical polyadic decomposition (CPD) of the input tensor, followed by performing a sparse factorization on the third factor matrix.