Pylons, 7 5 4 bytes
Picked a random language on TIO used it
46vt Explanation:
46 # No Stack is [4, 6] v # Reverse the stack [6, 4] t # take top of stack 4 Doubled:
4466 # Still no idea but resulting# stackStack is [4, 4, 6, 6] vv # Reverse the stack twice so it's the same [4, 4, 6, 6] tt # take top of stack 6 and again which is 6 again Saved 2 bytes thanks to officialaimm Saved
Saved 1 bytes thanks to * Veedrac* Veedrac