Retirement tax questions

I agree with Bill in that, in my case, TT noted the correct amount of $300.00 CC on line 10b of my form 1040-SR.  However, there is no amount listed on line 10a but the program did place $300.00 on line 6 of the SS Benefits Worksheet that caused the taxable social security amount to be reduced, in my case, by $255.00. I feel that this is "double dipping" the charitable contribution amount that is allowed by the IRS.  Bottom line is that my Adjusted Gross Income noted on line 11 of the 1040-SR return was reduced by $555.00 instead of the allowable $300.00.