Duplicate layer

`⌘ Cmd` + `D`

All hotkeys for Substance Painter (Mac)

General Hide Interface	`⭾ Tab`
General Undo	`⌘ Cmd` + `Z`
General Redo	`⌘ Cmd` + `Y`
General Mode Painting	`F9`
General Mode Rendering (Iray)	`F10`
General Open project	`⌘ Cmd` + `O`
General Close project	`⌘ Cmd` + `W`
General Save Project	`⌘ Cmd` + `S`
General Save As Project	`↑ Shift` + `⌘ Cmd` + `S`
General New project	`⌘ Cmd` + `N`
General Quit Application	`⌘ Cmd` + `Q`
General Increase tool size	`]`
General Decrease tool size	`[`
General grayscale tool	`Invert`
General Pick stroke material	`P`
General Symmetry	`L`
General Lazy Mouse	`D`
General Swap 2D / 3D view	`F4`
General Camera Perspective	`F5`
General Camera Orthographic	`F6`
General Display next channel	`C`
General Display material	`M`
General Display next additional map	`B`
General Toggle particles animation	`Space`
General Export textures	`↑ Shift` + `⌘ Cmd` + `E`
General Center the whole mesh	`F`
General Toggle quick mask edition	`U`
General Clear quick mask	`Y`
General Invert quick mask	`I`
General Viewport layout 3D/2D	`F1`
General Viewport layout 3D only	`F2`
General Viewport layout 2D only	`F3`
General Texture set isolate	`⌥ Option` + `Q`
General Select Paint tool	`1`
General Select Paint tool + Particles	`⌘ Cmd` + `1`
General Select Eraser tool	`2`
General Select Eraser tool + Particles	`⌘ Cmd` + `2`
General Select Projection tool	`3`
General Select Projection tool + Particles	`⌘ Cmd` + `3`
General Select Polygon Fill	`4`
General Select Smudge tool	`5`
General Select Clone tool (relative source)	`6`
General Select Clone tool (absolute source)	`⌘ Cmd` + `6`
Mouse shortcuts Use tool / paint	`Mouse left click`
Non-editable shortcuts Disable/Enable mask	`↑ Shift` + `Mouse left click`
Mouse shortcuts Draw straight lines with snapping	`Ctrl` + `↑ Shift` + `Mouse left click`
Mouse shortcuts Camera rotate	`⌥ Option` + `←`
Mouse shortcuts Camera snap rotate	`↑ Shift` + `⌘ Cmd` + `Mouse left click`
Mouse shortcuts Camera translate	`⌥ Option` + `⌘ Cmd` + `Mouse left click`
Mouse shortcuts translate (alternative)	`Camera`
Mouse shortcuts Camera zoom	`Mouse middle click`
Mouse shortcuts Stencil rotate	`S` + `Mouse left click`
Mouse shortcuts Stencil snap rotate	`↑ Shift` + `S` + `Mouse left click`
Mouse shortcuts Stencil zoom	`S` + `Mouse right click`
Mouse shortcuts Change tool Size / Hardness	`⌘ Cmd` + `Mouse right click`
Mouse shortcuts Change tool Flow / Rotation	`⌘ Cmd` + `Mouse left click`
Mouse shortcuts Rotate environment	`↑ Shift` + `Mouse right click`
Mouse shortcuts Texture set selection	`⌥ Option` + `⌘ Cmd` + `Mouse right click`
Mouse shortcuts Click in viewport Quick menu	`Mouse right click`
Mouse shortcuts Set Clone tool source location	`V` + `Mouse left click`
Other Ignore stencil mask	`N`
Other Resume previous stroke	`A`
Non-editable shortcuts Copy layer	`⌘ Cmd` + `C`
Non-editable shortcuts Cut layer	`⌘ Cmd` + `X`
Non-editable shortcuts Paste layer	`⌘ Cmd` + `V`
Non-editable shortcuts Delete layer	`Del`
Non-editable shortcuts Duplicate layer	`⌘ Cmd` + `D`
Non-editable shortcuts Group layer	`⌘ Cmd` + `G`
Non-editable shortcuts Copy layer content	`⌥ Option` + `⌘ Cmd` + `C`
Non-editable shortcuts Paste layer content	`⌥ Option` + `⌘ Cmd` + `V`
Non-editable shortcuts Display mask in viewport	`⌥ Option` + `Mouse left click`
Non-editable shortcuts Cycle through the cameras	`← →`
Non-editable shortcuts Show/hide	`Q`
Non-editable shortcuts Translate	`W`
Non-editable shortcuts Rotate	`E`
Non-editable shortcuts Scale	`R`
Non-editable shortcuts Change (object/world)	`T`
Non-editable shortcuts Decrease/Increase size	`-`
Non-editable shortcuts Decrease/Increase size	`+`
Non-editable shortcuts (hold) Snapping On	`↑ Shift`
Non-editable shortcuts Symmetrical selection	`⌘ Cmd`
Non-editable shortcuts Drag & drop	`⌘ Cmd` + `Mouse movement`