In other words, is the following true? $$\int_0^\infty f(t)e^{-st}\, dt=\int_0^\infty g(t)e^{-st}\, dt\implies f(t)=g(t)$$
If not, what are examples of different functions with the same Laplace transforms (other than those that differ by a constant)?
No. Take
$$f(t)=0$$
and
$$g(t) = \begin{cases} 1 & t=1 \\ 0 & t\neq 1 \\ \end{cases}$$ They are different functions with the same Laplace transform.