Thanks Herbert, yes I did own both on the same address with the same outputs.  How does a replay attack happen and why wouldn't it have happened on the first two test transactions?  Thank you for your help. 

I did two test transactions of .1 Bitcoin SV to my Poloniex wallet that worked fine.  Then when I went to transfer 4 Bitcoin SV it sent, but a second transaction of BCH was sent 20 minutes later to the Bitcoin SV wallet on Poloniex.  I don't understand how this could have happened and now I appear to have lost the 4 BCH.  Can anyone help me understand how this could have happened and if there is a way to recover the coins.  This is a lot of money for me.  Thanks in advance for your help.