QB Issue Resolution:
So sorry to hear that your previous QuickBooks version has been deleted during the install of QuickBooks 2015. I will properly escalate and submit report on this issue.
Just a note, did you choose Express Install or Custom & Network Options. If the former has been selected, it will override the existing installation, to avoid this to happen, we recommend the latter.
Resolution for Issue 'Why does QB Pro 2015 delete prior year QB with standard install? Bad design!' available: Yes (Solved).
Source: Intuit Community forum.
Why does QB Pro 2015 delete prior year QB with standard install? Bad design!: 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 install
Quickbooks Repair Pro will resolve it efficiently and affordably. Guaranteed resolution of your issue, or you pay nothing!
Error Recovery for install [Canada]
E-Tech is the #1 Quickbooks data migration and Conversion service provider.
Additional Support Options: