Thank you @Wile_E_Coyote . I have written a small macro (by taking some online help) to fit double gaussian peak using parameters obtained from single fit data.
double_peak_fit_57Co.root (41.0 KB)
Here are few output statements:
gaus peak integral1 = 590800 ± 774.567
gaus peak integral2 = 63938.9 ± 250.478
ChiSquare= 570.468 NDf= 39 ChiSquare/NDf=14.6274
Does the values look reasonable for chisquare/NDF and errors?