This is interesting, because I never knew that you could have two modules both declaring a Public Type with the same name. Now that I do know, I'm horrified.
So first, Eric Towers is correct that you want to put your Type declaration in only one module. Other modules that use this Type will depend on that module being available, but that's just something that comes with modularization. The need to manage dependencies between modules is common to all software development. It's unfortunate that within a single VBA project (like the kind you'd find in a single Excel workbook) the only option for managing module dependencies is manual. (In VBA, "modules" are really "source code files". Other languages/environments have various higher-level packaging systems.)
Now for the horrifying part. If you do declare Types with the same name in different modules, you're setting yourself up for problems. Consider two VBA Modules:
'Module1
Public Type typ
x As String
End Type
Public Sub useTyp()
Dim t As typ
t.x = 42
Debug.Print t.x + t.x
End Sub
and
'Module2
Public Type typ
x As Long
End Type
Public Sub useTyp()
Dim t As typ
t.x = 42
Debug.Print t.x + t.x
End Sub
in the same project, your code will "compile" (at least in Excel VBA). But the two 'useTyp' subs give different output. Worse, if you remove one of the Type declarations from one of the modules, you've suddenly changed the behavior of the 'useTyp' routine in the same module! This kind of ambiguity is never desirable.
What's going on is that VBA is really creating two different types, 'Module1.typ', and 'Module2.typ'. When you're in the same module and don't qualify the type name, VBA silently finds the "right" type and uses it.
I'm a little surprised to hear that you're passing around instances of one 'XYpointType' to modules that have a different 'XYpointType' declaration. It's not that important, but could you post the code? I'm interested in nitpicky things like this...