Non-uniqueness of continuous time sinusoids?
In discrete-time we have

$$e^{j\omega_0n}=e^{j(\omega_0+2\pi k)n},\quad \forall n$$

because $2\pi kn$ is an integer multiple of $2\pi$ if $k$ and $n$ are integers, and, consequently, $e^{j2\pi kn}=1$. In continuous time you generally have

$$e^{j\omega_0t}\neq e^{j(\omega_0+2\pi k)t}$$

because $2\pi k t$ is (for arbitrary $t$) not an integer.