Wix Upgrade Code
Building a WiX msi installer resulted in duplicate installation when a new version was installed. This was strange, then I have made sure to provide an upgrade code like so:
1<Product Id="*"
2 Language="1033"
3 UpgradeCode="DB9B0021-ED5D-4E9F-B17F-34A72D2D9689"
4 Manufacturer="[Copy Right Info]"
5 Name="[Product Name]"
6 Version="1.0.1">
The problem was happening after I have added <ServiceInstall ...> to my primary component.
The solution
adding MajorUpgrade to the Product did the trick:
1<MajorUpgrade
2 Schedule="afterInstallInitialize"
3 DowngradeErrorMessage="A later version of [ProductName] is already installed. Setup will now exit." />