  We consider the properties of massive one particle states on a translation
covariant Haag-Kastler net in Minkowski space. In two dimensional theories,
these states can be interpreted as soliton states and we are interested in the
existence of antisolitons. It is shown that for each soliton state there are
three different possibilities for the construction of an antisoliton sector
which are equivalent if the (statistical) dimension of the corresponding
soliton sector is finite.
