Copying equation-environment produces "destination with the same id"

Question

I used to typeset short exact sequences as equations. Now I want to reference to a short exact sequence by "seq." and not "eq." Therefore, I defined a new environment "ses" with an alias counter "sesC" and changed creflabelformat and crefname accordingly (Took me a while to get it working). Here is an example:

\documentclass{article}
\usepackage{amsmath} % needed for its \numberwithin command
\usepackage{hyperref}
\usepackage[nameinlink]{cleveref}
\usepackage{aliascnt}

\newaliascnt{sesC}{equation}
\aliascntresetthe{sesC}

\newenvironment{ses}[1]{\refstepcounter{sesC}\label{ses:#1}\equation}{\tag{\thesesC}\endequation}
\crefname{sesC}{seq.}{seqs.}
\creflabelformat{sesC}{#2\textup{(#1)}#3}

\begin{document}
    \begin{equation}
        x=y \label{eq}
    \end{equation}

    \begin{ses}{test}
        A\to B \to C
    \end{ses}
    Reference to the equation: \cref{eq}\\
    Reference to the sequence: \cref{ses:test}\\
    Reference to the other equation: \cref{eq2}\\

    \begin{equation}
        y=z \label{eq2}
    \end{equation}
\end{document}

This produces, as desired,

But it also produces

pdfTeX warning (ext4): destination with the same identifier (name{equation.0.3}) has already used, duplicate ignored

If I'm not mistaken, hyperref has a problem with the repeated use of the same counter. I don't really understand this; no two environments have the same numeration. What am I doing wrong?

Edit: To make more precise what I want to accomplish: I want "new" equations which are enumerated like normal equations and look like equations, but which are quoted by cleveref as "sequences"