Form 1040, Line 25b. Where does this amount come from?

in a complete file there is tax payments worksheet.  there is a subsection that says "taxes withheld from" and indicates which type of forms reported the withholding. it does not indicate the specific form only the type

Line 25b is federal withholding from any 1099 forms you got like 1099G or 1099R box 4.   Is 25b too much?  Did you import any 1099 forms and also enter them manually?

I need to delete a double entry Form 1040 page 2 Line 25b

Then you have to find the duplicate 1099 form or SSA-1099.  There might be other amounts that are duplicated too.