different session contents for the same session, CF9

Two URLs:

http://DOMAIN/zshowsession.cfm

http://DOMAIN/institutes/office/zshowsession.cfm

The DOMAIN portion is identical.  Same site.  Same CF server.

Both files contain this code:

<cfdump var="#session#">

One outputs this:

The other outputs this:

You can see it's the same cfid and cftoken, but the contents of session are different.  This is causing me problems.

Is anyone aware of any legitimate reason why this would be happening?  Maybe some weird CF configuration in the CFIDE or something?  I already checked the two relevant Application.cfc files (one in /, one in /institutes) and there is nothing that modifies the session.