Excel VBA: Dictionary: Can I: Delete 'used entries' while iterating thru Keys RESOLVE

[Webtest]

Esteemed Forum Participants and Lurkers:
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Excel 2003 VBA

I am doing some relatively low level 'artificial intelligence', and I think the easiest way achieve my objective is to make a pair of dictionaries, and to iterate through 1 of the dictionaries checking for matching entries in the second dictionary. What I need to do in the case of a match, is to REMOVE both of the dictionary entries.

The question is: "is it safe to REMOVE dictionary entries WHILE ITERATING through the dictionary ???"

If this is UNwise, I need to rethink my whole approach.

Here is a code snippet:

    For Each aKey In PROGd.keys
        'Check for a matching key in the DISTRO Dictionary
        If DISTd.exists(aKey) Then
            'We are DONE with these keys, so delete them!
            PROGd(aKey).Remove
            DISTd(aKey).Remove
        End If
    Next aKey

It is actually a whole lot more complex than this code, but what I am doing is looking for exceptions where 2 lists do NOT match. When I get done iterating through 1 dictionary, the remainders in both dictionaries are all of the exceptions that I need to harpoon.

Thank you for any and all comments, suggestions, and assistance.