Exceptions in log when creating new tags

[jonescc]

To Reproduce

Create a new tag

What happens

Tag is saved but get following exceptions in the log:

org.hibernate.HibernateException: Found two representations of same collection: au.org.emii.aatams.Tag.sensors
	at com.sun.proxy.$Proxy18.flush(Unknown Source)
	at au.org.emii.aatams.SensorController$_closure5.doCall(SensorController.groovy:57)
	at au.org.emii.aatams.SensorController$_closure5.doCall(SensorController.groovy)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.executeChain(AbstractShiroFilter.java:359)
	at org.apache.shiro.web.servlet.AbstractShiroFilter$1.call(AbstractShiroFilter.java:275)
	at org.apache.shiro.subject.support.SubjectCallable.doCall(SubjectCallable.java:90)
	at org.apache.shiro.subject.support.SubjectCallable.call(SubjectCallable.java:83)
	at org.apache.shiro.subject.support.DelegatingSubject.execute(DelegatingSubject.java:344)
	at org.apache.shiro.web.servlet.AbstractShiroFilter.doFilterInternal(AbstractShiroFilter.java:272)
	at org.apache.shiro.web.servlet.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:81)
	at org.apache.shiro.grails.SavedRequestFilter.doFilter(SavedRequestFilter.java:55)
	at java.lang.Thread.run(Thread.java:745)

What I expect to happen

Tag is saved without throwing exceptions.

[jonescc]

Believe this was introduced by acd4f51