Solution (source code)

= Solution

The equation $u=v'$ fixes $u$ from the same two constants:
$$
\boxed{u(t)=2Ae^{2t}-2Be^{-2t}.}
$$
Indeed $u'=4Ae^{2t}+4Be^{-2t}=4v+2$, so both original equations hold. No further independent integration constant is available in this two-dimensional <linear system of ordinary differential equations>.