Squint surgery aims to align your eyes by strengthening or weakening the muscles that move the eyeballs. Since both eyes work together, it is possible to correct the squint in one eye by surgery on the same or both eyes. In your case, since one eye is already operated upon, the residual squint can be corrected by surgery on the other eye.
You haven't mentioned other details, especially your vision in the squinting eye and if there is occurrence of double vision. But I would presume that the surgery is for cosmetic reasons.
Next Steps
Please discuss the surgical plan with your Ophthalmologist and have realistic expectations about the result.