The following is a (fairly) minimal example:

```
\documentclass{book}
\usepackage{amsmath}
\usepackage{amsthm}
\usepackage{thmtools}
\declaretheoremstyle[
spaceabove=6pt, spacebelow=6pt,
headfont=\normalfont\bfseries,
notefont=\itshape, notebraces={(}{)},
bodyfont=\itshape,
postheadspace=1em
]{mystyle}
\declaretheorem[name=Theorem, parent=section, style=mystyle,
refname={Theorem,Theorems},
Refname={Theorem,Theorems}]{theorem}
\declaretheorem[name=Proposition, sibling=theorem, style=mystyle,
refname={Proposition,Propositions},
Refname={Proposition,Propositions}]{prop}
\usepackage{hyperref}
\hypersetup{%
colorlinks = true,
linkcolor = blue,
urlcolor = magenta,
citecolor = red,
pdfpagemode = UseNone,
pdfpagelayout = SinglePage,
pdfdisplaydoctitle = true,
plainpages = false}
\usepackage[capitalize]{cleveref}
\crefname{prop}{Proposition}{Propositions}
\begin{document}
\begin{prop}\label[prop]{prop:112}
Testing this out!
\end{prop}
\begin{prop}\label[prop]{prop:113}
Still Testing!
\end{prop}
\cref{prop:112} and \cref{prop:113}
\end{document}
```

The problem is that both links point to the first proposition. I also get the error

`destination with the same identifier (name{prop.\\theHprop\040}) has been already used, duplicate ignored`

.

Does anyone know what steps I need to take to resolve this problem (I thought I had already done enough!). Perhaps it is pertinent, but I also get the error

`Package thmtools warning: Your version of cleveref is too old!`

but I just updated both packages!

## Best Answer

Your example works properly for me. (No log file messages from thmtools). Package versions