Two circuits for one domain (Circuit visualizer sometimes shows the "wrong" exit node)

Making an arbitrary number of new circuits (either with the new identity button or when the Tor client creates circuits while browsing) eventually causes the circuit view in Torbutton to show the wrong exit node.

I have noticed this in Tor Browser 5.0.3 through Tor Browser 5.0.7

A far as I can tell, this is not related to architecture or OS nor to my network or even to machines owned by me. Also the problem is not limited to any particular website and it has nothing to do with JavaScript. I noticed this on Linux 64-bit and 32-bit on every Tor Browser version above and Windows 64-bit and 32-bit on version 5.0.3 (I've not checked since then). However I have not tested this in Mac OS X at all.

When testing this I found that the number of new circuits that are needed to reproduce this varies. Sometimes it happened first time I visited check.torproject.org, other times I spent 10-15 minutes creating new identities.

A screenshot can be found on stack exchange. https://tor.stackexchange.com/questions/9460/why-does-torbutton-circuit-view-not-consistently-show-the-correct-exit-node