  The tangential velocity dispersion of stars belonging to the Milky Way
globular cluster's tidal tails has recently been found from N-body simulations
to be a parameter that distinguishes between cored and cuspy profiles of
low-mass dwarf galaxy dark matter subhaloes where that globular cluster formed,
and the in-situ formation scenario. In this context, we discovered that M5's
tidal tails are composed by stars at two different metallicity regimes ([Fe/H]
~ -1.4 dex and -2.0 dex). The more metal-rich tidal tail stars are of the same
metal content than M5's members and have a tangential velocity dispersion that
coincides with the predicted value for a cuspy formation scenario (subhalo mass
$\sim$ 10$^9$ M$_{\odot}$). The more metal-poor stars, that are found along the
entire M5 tidal tails and have similar distributions to their more metal-rich
counterparts in the M5 colour-magnitude diagram and orbit trajectory, have a
tangential velocity dispersion that refers to a cored subhalo (mass $\sim$
10$^9$ M$_{\odot}$) or an in-situ formation scenario. In order to reconcile the
dual distribution of M5 tidal tail stars, in kinematics and chemistry, we
propose that M5 collided with another more metal-poor and less massive globular
cluster anytime before or after it was accreted into the Milky Way.
