Wix installs package instead updating

Question

I build new package of program, and compile new msi. Then I try to update program, already installed on PC, but last msi installs one more program instead updating old version

If ProductVersion in wxs doesn't change, it shows repaid dialog. If it is changed, it installs program instead old. But if new package is built, msi installs one more instance of program

 <Product Id="*" 
          UpgradeCode="$(var.UpgradeCode)"
          Name="$(var.ProductName)"
          Version="$(var.ProductVersion)"
          Manufacturer="$(var.Manufacturer)"
          Language="1033">

    <Package InstallerVersion="405"
             Compressed="yes"
             InstallScope="perMachine"
             Languages="1033"
             Comments="Windows Installer Package"/>
    <Media Id="1" Cabinet="product.cab" EmbedCab="yes"/>

    <MajorUpgrade DowngradeErrorMessage="A newer version of $(var.ProductName) is already installed." />

    <UI Id="UserInterface">

      <Property Id="WixUI_Mode" Value="InstallDir" />
      <Property Id="DefaultUIFont" Value="WixUI_Font_Normal" />
      <Property Id="ARPNOMODIFY" Value="1" />
...

      <Publish Dialog="BrowseDlg" Control="OK" Event="DoAction" Value="WixUIValidatePath" Order="3">1</Publish>
      <Publish Dialog="BrowseDlg" Control="OK" Event="SpawnDialog" Value="InvalidDirDlg" Order="4"><![CDATA[NOT WIXUI_DONTVALIDATEPATH AND WIXUI_INSTALLDIR_VALID<>"1"]]></Publish>
      <Publish Dialog="ExitDialog" Control="Finish" Event="EndDialog" Value="Return" Order="999">1</Publish>
      <Publish Dialog="WelcomeDlg" Control="Next" Event="NewDialog" Value="LicenseAgreementDlg">NOT Installed AND NOT PATCH</Publish>
      <Publish Dialog="WelcomeDlg" Control="Next" Event="NewDialog" Value="VerifyReadyDlg">PREVIOUSVERSIONSINSTALLED OR Installed AND PATCH</Publish>
      <Publish Dialog="LicenseAgreementDlg" Control="Back" Event="NewDialog" Value="WelcomeDlg">1</Publish>
      <Publish Dialog="LicenseAgreementDlg" Control="Next" Event="NewDialog" Value="InstallDirDlg">LicenseAccepted = "1"</Publish>
      <Publish Dialog="InstallDirDlg" Control="Back" Event="NewDialog" Value="WelcomeDlg">1</Publish>
      <Publish Dialog="InstallDirDlg" Control="Next" Event="SetTargetPath" Value="[WIXUI_INSTALLDIR]" Order="1">1</Publish>
      <Publish Dialog="InstallDirDlg" Control="Next" Event="DoAction" Value="WixUIValidatePath" Order="2">NOT WIXUI_DONTVALIDATEPATH</Publish>
      <Publish Dialog="InstallDirDlg" Control="Next" Event="SpawnDialog" Value="InvalidDirDlg" Order="3"><![CDATA[NOT WIXUI_DONTVALIDATEPATH AND WIXUI_INSTALLDIR_VALID<>"1"]]></Publish>
      <Publish Dialog="InstallDirDlg" Control="Next" Event="NewDialog" Value="VerifyReadyDlg" Order="4">WIXUI_DONTVALIDATEPATH OR WIXUI_INSTALLDIR_VALID="1"</Publish>
      <Publish Dialog="InstallDirDlg" Control="ChangeFolder" Property="_BrowseProperty" Value="[WIXUI_INSTALLDIR]" Order="1">1</Publish>
      <Publish Dialog="InstallDirDlg" Control="ChangeFolder" Event="SpawnDialog" Value="BrowseDlg" Order="2">1</Publish>
      <Publish Dialog="VerifyReadyDlg" Control="Back" Event="NewDialog" Value="InstallDirDlg" Order="1">NOT Installed</Publish>
      <Publish Dialog="VerifyReadyDlg" Control="Back" Event="NewDialog" Value="MaintenanceTypeDlg" Order="2">Installed AND NOT PATCH</Publish>
      <Publish Dialog="VerifyReadyDlg" Control="Back" Event="NewDialog" Value="WelcomeDlg" Order="2">Installed AND PATCH</Publish>
      <Publish Dialog="MaintenanceWelcomeDlg" Control="Next" Event="NewDialog" Value="MaintenanceTypeDlg">1</Publish>
      <Publish Dialog="MaintenanceTypeDlg" Control="RepairButton" Event="NewDialog" Value="VerifyReadyDlg">1</Publish>
      <Publish Dialog="MaintenanceTypeDlg" Control="RemoveButton" Event="NewDialog" Value="VerifyReadyDlg">1</Publish>
      <Publish Dialog="MaintenanceTypeDlg" Control="Back" Event="NewDialog" Value="MaintenanceWelcomeDlg">1</Publish>
    </UI>

Answer 1

Decision was to add

 AllowSameVersionUpgrades="yes"

to MajorUpgrade