If any developer has the older version of Glance Screen (System) app for windows phone then you are hereby requested to kindly provide the same.
First of all, any Developer other than Microsoft won't be having the .xap file of the previous versions of Glance Screen.
Secondly even if you have the .xap file and you place it on your SD Card, you will not be able to install it on your phone, because when you would try to install it, your phone checks the store whether there is a latest version of the Glance Screen. If there is(which there is), your phone would start downloading the latest version of Glance Screen, not installing the one on your SD Card.
Also I don't think side loading the app through Developer Unlock will work as it is a system app.