Where there is a question whether a person did a particular act or had a particular state of mind and it is reasonably open to find that—
(a) the person did some other particular act or had some other particular state of mind, respectively; and
(b) all the acts or states of mind, and the circumstances in which they were done or existed, are substantially and relevantly similar,
the tendency rule does not prevent the admission or use of evidence that the person did the other act or had the other state of mind, respectively.