  Reversing Petri nets (RPNs) have recently been proposed as a
net-basedapproach to model causal and out-of-causal order reversibility. They
are based on the notion of individual tokens that can be connected together via
bonds. In this paper we extend RPNs by allowing multiple tokens of the same
type to exist within a net based on the individual token interpretation of
Petri nets. According to this interpretation, tokens of the same type are
distinguished via their causal path. We develop a causal semantics of the model
and we prove that the expressive power of RPNs with multiple tokens is
equivalent to that of RPNs with single tokens by establishing an isomporphism
between the Labelled Transition Systems (LTSs) capturing the reachable parts of
the respective RPN models.
