\documentclass[a4paper,ngerman]{scrartcl}
\usepackage[ngerman]{babel}
\usepackage[pdftex,bookmarksnumbered,bookmarksopen]{hyperref}
\usepackage{float}
% patch of float's \caption to avoid double anchor setting
% by \refstepcounter of float's \caption and in hyperref's
% \@caption.
% tested for (hyperref 2003/01/22 v6.73n, float 1999/05/29 v1.2d)
% and (hyperref 2002/05/27 v6.72r, float 2001/11/08 v1.3d).
\begingroup
  \makeatletter
  \def\x#1\refstepcounter#2\@nil{%
    \endgroup
    \def\caption{#1\H@refstepcounter#2}%   
  }%
\expandafter\x\caption\@nil

\listfiles
\begin{document}

\section{Abschnitt 1}
\begin{table}[ht]
\caption{Tabelle 1}
\end{table}

\section{Abschnitt 2}
\begin{figure}[ht]
\caption{Abbildung 1}
\end{figure}

\end{document}