Got IRS notice cp2000 for year 2017. 1099-R form related

Got IRS notice cp2000 for year 2017.

 

I contributed 2 times in IRA and then converted to ROTH in 2017 ( for backdoor roth).  One in April 2017 for year 2016. Other is July 2017 for year 2017.

 

Problem is Merrill sent two contributions of $5500  for year 2017 to IRS . There are two 1099-R forms. 1099-R of year 2017  BOX 7 says 2 in both forms

Now IRS says one $5500 is taxable retirement income and applying tax on this amount.  What can be done in this case ?