All of the following is on 64bit MEP 2011 using the same drawing/object that I used in the 32bit tests above
Test 1:
(vlax-invoke-method (vla-get-Utility (vla-get-ActiveDocument
(vlax-get-acad-object))) 'GetObjectIdString (vlax-ename->vla-object (car
(entsel))) [color=red]:vlax-false[/color])
32bit: "2130071024"
64bit: "8796083987552"
(vlax-invoke-method (vla-get-Utility (vla-get-ActiveDocument
(vlax-get-acad-object))) 'GetObjectIdString (vlax-ename->vla-object (car
(entsel))) [color=red]:vlax-true[/color])
32bit: "7EF64DF0"
64bit: "000007FFFF762460"
Test 2:
(vlax-invoke (vla-get-Utility (vla-get-ActiveDocument
(vlax-get-acad-object))) 'GetObjectIDString (vlax-ename->vla-object (car
(entsel))) [color=red]:vlax-true[/color])
32bit: "7EF64DF0"
64bit: "000007FFFF762460"
(vlax-invoke (vla-get-Utility (vla-get-ActiveDocument
(vlax-get-acad-object))) 'GetObjectIDString (vlax-ename->vla-object (car
(entsel))) [color=red]:vlax-false[/color])
32bit: "7EF64DF0"
64bit: "000007FFFF762460"
Test 3:
(vlax-invoke (vla-get-Utility (vla-get-ActiveDocument
(vlax-get-acad-object))) 'GetObjectIDString (vlax-ename->vla-object (car
(entsel))) [color=red]acFalse[/color])
32bit: "2130071024"
64bit: "8796083987552"
(vlax-invoke (vla-get-Utility (vla-get-ActiveDocument
(vlax-get-acad-object))) 'GetObjectIDString (vlax-ename->vla-object (car
(entsel))) [color=red]acTrue[/color])
32bit: "7EF64DF0"
64bit: "000007FFFF762460"