I have not found a way to do this. Once I assign a Contact to an Account,
that one is no longer available to use again. I tried one thing that worked,
but may not be feasible, I created three Contact records, one for each
Account, but used the Company field (not the Account field) and typed in each
different Company name. Then I opened the File As box and chose LN, FN,
(Company Name) as the File As.
So now when I search for JONES, I get Jones, Ralph (Company A); Jones, Ralph
(Company B) and Jones, Ralph (Company C). Because the Company field is
different for each one, I have not yet overwritten this info when I check for
dups (like when I'm importing more/new data). And you can associate one of
Jones, Ralphs to an Account, just repeat that info in the Company field. Not
elegant, but it works for me, for now.