QB Issue Resolution:

You would keep both if you downloaded 2016 and didn’t overwrite 2012.

Resolution for Issue 'How can I reinstall quickbooks pro 2016 is an upgrade so now I don’t have the 2012 version anymore on my PC for the upgrade. Is there a work around?' available: Yes (Solved).
Source: Intuit Community forum.

How can I reinstall quickbooks pro 2016 is an upgrade so now I don’t have the 2012 version anymore on my PC for the upgrade. Is there a work around?: this issue or error code is a known issue in Quickbooks Online (QBO) and/or Quickbooks. Support for this issue is available either by self-service or paid support options. Experts are available to resolve your Quickbooks issue to ensure minimal downtime and continue running your business. First try to resolve the issue yourself by looking for a resolution described below. If it is a complex issue or you are unable to solve the issue, you may contact us by clicking here or by using other support options.

Support for 2012 version
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Error Recovery for 2012 version [Canada]
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