Let Mirror at the same value as before, so less headhache with update material

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/LayeredLit/LayeredLit.shader

         [ToggleOff] _EnableBlendModePreserveSpecularLighting("Enable Blend Mode Preserve Specular Lighting", Float) = 1.0
 
         [ToggleOff] _DoubleSidedEnable("Double sided enable", Float) = 0.0
-        [Enum(Mirror, 0, Flip, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
+        [Enum(Flip, 0, Mirror, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
         [HideInInspector] _DoubleSidedConstants("_DoubleSidedConstants", Vector) = (1, 1, -1, 0)
 
         [Enum(Subsurface Scattering, 0, Standard, 1)] _MaterialID("MaterialId", Int) = 1 // MaterialId.RegularLighting

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/LayeredLit/LayeredLitTessellation.shader

         [ToggleOff] _EnableBlendModePreserveSpecularLighting("Enable Blend Mode Preserve Specular Lighting", Float) = 1.0
 
         [ToggleOff] _DoubleSidedEnable("Double sided enable", Float) = 0.0
-        [Enum(Mirror, 0, Flip, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
+        [Enum(Flip, 0, Mirror, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
         [HideInInspector] _DoubleSidedConstants("_DoubleSidedConstants", Vector) = (1, 1, -1, 0)
 
     	[Enum(Subsurface Scattering, 0, Standard, 1)] _MaterialID("MaterialId", Int) = 1 // MaterialId.RegularLighting

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/Lit.shader

         [ToggleOff] _EnableBlendModePreserveSpecularLighting("Enable Blend Mode Preserve Specular Lighting", Float) = 1.0
 
         [ToggleOff] _DoubleSidedEnable("Double sided enable", Float) = 0.0
-        [Enum(Mirror, 0, Flip, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
+        [Enum(Flip, 0, Mirror, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
         [HideInInspector] _DoubleSidedConstants("_DoubleSidedConstants", Vector) = (1, 1, -1, 0)
 
         [Enum(UV0, 0, Planar, 4, TriPlanar, 5)] _UVBase("UV Set for base", Float) = 0

ScriptableRenderPipeline/HDRenderPipeline/HDRP/Material/Lit/LitTessellation.shader

         [ToggleOff] _EnableBlendModePreserveSpecularLighting("Enable Blend Mode Preserve Specular Lighting", Float) = 1.0
 
         [ToggleOff] _DoubleSidedEnable("Double sided enable", Float) = 0.0
-        [Enum(Mirror, 0, Flip, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
+        [Enum(Flip, 0, Mirror, 1)] _DoubleSidedNormalMode("Double sided normal mode", Float) = 1
         [HideInInspector] _DoubleSidedConstants("_DoubleSidedConstants", Vector) = (1, 1, -1, 0)
 
         [Enum(UV0, 0, Planar, 4, TriPlanar, 5)] _UVBase("UV Set for base", Float) = 0