最近同事的项目中，

打开一个页面的时候，发现

那么一个页面可以有多少个Web Part呢？

The limit is customizable in web.config file,
50 (default) - http://technet.microsoft.com/en-us/library/cc262787.aspx
100 (recommended max) - http://technet.microsoft.com/en-us/library/cc287743.aspx

最终的原因参考

http://vivek-soni.blogspot.com/2010/08/duplicate-web-parts-shown-in-sharepoint.html

Issue:
Using the same
web part zone GUID multiple times whether in same page layout or a different
page layout would result into the web part being shown up multiple times.

Resolution:

Ensure that
every web part zone and web part in your page layouts have a unique GUID across
your site collection.