Let \( f \) and \( g \) be two distinct normalized Hecke eigenforms of even integral weights for the full modular group \( \textrm{SL}_2(\mathbb {Z}) \) . Fix integers \( \ell , \mathfrak {u} \geqslant 3 \) . We obtain asymptotic formulas for the sums of the coefficients of an \( L \) -function constructed by applying the \( \ell \) -fold to \( f \) and the \( \mathfrak {u} \) -fold to \( g \) , evaluated at integers \( n \leqslant X + 1 \) satisfying \( n \equiv 1 \ (\textrm{mod}\,{q}) \) . Furthermore, we investigate shifted convolution sums of these coefficients, employing a kernel function that extends the analytic framework originally developed by Ivić and Tenenbaum.