  In the context of the full line Schrodinger equation, we revisit the binary
Darboux transformation (double commutation method) which inserts or removes any
number of positive eigenvalues embedded into the absolutely continuous spectrum
without altering the rest of scattering data. We then show that embedded
eigenvalues produce an additional explicit term in the KdV solution. This term
looks similar to multi-soliton solution and describes waves traveling in the
direction opposite to solitons. It also resembles the known formula for
(singular) multi-positon solutions but remains bounded, which answers in the
affirmative Matveev's question about existence of bounded positons.
