Google Analytics wrongly records events when using Internet Explorer

I’m a web designer and came across an odd finding. On our website, we track our contact form submissions using Google Tag Manager & Google Analytics.

I noticed that every once in a while the number of submissions recorded by Google Analytics is higher than the actual amount of messages we received.

So, according to Analytics, we should have received 5 submissions last week – when in fact, we just received 2 messages. (From this page: https://avinton.com/services/avinton-data-platform/)

The tracking setup seems to be correct (and has been correctly tracking submissions for over a year). So, I did a lot of digging and finally found out that all those "ghost" submissions were visitors using Internet Explorer. In December, we even had 2 recorded form submissions in Analytics, originating from pages without ANY contact forms on them! (such as https://avinton.com/blog/2017/10/clustering/)

While Internet Explorer totally messes up the page’s CSS, I successfully received my own test message. So the form seems to work, at least in my IE version.

So, does that mean some version of Internet Explorer wrongly fires events? Or did visitors actually try to send us a message which didn’t get through? Any suggestions on what to look at next are greatly appreciated!