How to replace menu key with capslock and capslock with left control using xkb

Question

I followed the instruction here by defining my own xkbsymbols

partial modifier_keys
xkb_symbols "replace_Menu_Capslock" {
replace key <COMP>  { [ Caps_Lock ] };
replace key <CAPS>  { [ Control_L ] };
}; 

The menu key now becomes Caps_Lock, but the <CAPS> key (original caps_lock key) is still Caps_Lock. Any thought on why replace works for <comps> but not for <caps>? Thank you very much!