Wrong numberformat assignment
*Created originally on Bitbucket by [zeripath (Andrew Thornton)](https://bitbucket.org/%7B281f6510-4f76-4967-8327-a0195489bb7d%7D/)*
Hi!
First of all thank you for your work.
There appears to be a bug in the way numberformats are applied in stylesheets. The two attached xlsx files are the same except in the broken case within `xl/styles.xml` :
```
#!xml
<numFmts count="3">
<numFmt numFmtId="164" formatCode="General"/>
<numFmt numFmtId="165" formatCode="General"/>
<numFmt numFmtId="166" formatCode="DD\/MM"/>
</numFmts>
```
whereas in the not broken case:
```
#!xml
<numFmts count="3">
<numFmt numFmtId="164" formatCode="General"/>
<numFmt numFmtId="165" formatCode="0"/>
<numFmt numFmtId="166" formatCode="DD\/MM"/>
</numFmts>
```
And with a little more testing, it appears that any duplicated formatCode will lead to errors in the interpretation of numFmts greater than that duplication.
*Attachments:* [broken.xlsx](/uploads/c4cd86209f49b60656883386516425ba/broken.xlsx)[not-broken.xlsx](/uploads/41a9d0c9429815c514a6715362ca786e/not-broken.xlsx)
issue