edit: Koen Vroeijenstijn pointed out that it's must faster to use the string table for an attribute and then you don't have to check for duplicates. Here is a code snippet:
geo=hou.node("./IN_shapes").geometry()
menuList=[]
attrib=geo.findPointAttrib("name")
names=attrib.strings()
for name in names:
menuList.append(name)
menuList.append(name)
return menuList
https://www.dropbox.com/s/95ikzajj4zmxtad/menu.hiplc?dl=0