In “5 Things to Think About Before Deploying Adobe Reader or Acrobat X” I mentioned that…
Prior to version X, Adobe did not support a configuration where both Reader and Acrobat are installed on the same system; this is now a supported configuration. If you want to deploy this way, you’ll want to decide which product is the default for viewing PDF files before you deploy them both.
To help clarify that, I’d like to explain exactly how to do this.
When you are configuring your install of Acrobat X using the Customization Wizard, the “Installation Options” panel asks you to select a “Default viewer for PDF files”. When you let the installer “decide which product will be the default”, nothing is saved in the customized build and the installer will show a checkbox (checked by default) for taking ownership of PDF files. If instead you choose the second option i.e. “Make Acrobat the default PDF viewer”, no option is shown to change the ownership and Acrobat will take ownership of PDF files.
So if Reader X is already present on the system and then Acrobat is installed, it will take ownership silently without showing the checkbox to change/retain ownership with the original product i.e. Reader X in this case.
Similarly when configuring Reader X using Customization Wizard, the “Installation Option” pane shows two options i.e. let “Installer decide which product will be default” and “Make Reader the default PDF viewer”. If you choose the former, the Reader X installer will show a checkbox (checked by default) for taking ownership of PDF files. However if you choose to “make Reader the default PDF viewer”, no checkbox is shown to change ownership and Reader X will be made the default viewer of PDF files.
If you want your users to have both Acrobat X & Reader X on a machine and want to keep one of these as default for PDF files and workflows, then customize that application installer using Customization Wizard and choose the option to make the application as default PDF viewer and deploy on users machine.
I hope this helps.