Is having a conventional marriage and a same sex civil union simultaneously,bigamy?

It is at the least morally wrong!

Depends on whether the state you're living in recognizes same-sex marriages. If not, then technically it's not bigamy, but I would recommend that the "offender" come clean with the person with whom he/she would like to terminate the relationship before the local media gets ahold of the information!

legally NO it is not bigamy because same sex marriages are not recognised by legal law.

Emotionally YES thats a no brainer.

A civil union is not a marriage ... right ?

If your State recognized same sex marriages .. and .. you were already married ... and you married again - then it would be bigamy.

Being married ... then just claiming a union - is just cheating.

yes

It would be big of me to answer a question like that.

Not if you are a Moron er Mormon. LOL

yes it is.