Why it is not permitted to make multi currency transactions for same Party?

I need to know what is the effect if I remove the validation on party currency and make the system accepts transactions on more than one account for same party each with different currency.

For example I need to make some transactions for Customer in EGP currency in account Debtors
and some times I need to make transactions for same Customer in account Debtors-EUR in Euro currency,
and some times I need to make transactions for same Customer in account Debtors-USD in US$ currency.

Please advice.

Same Issue with me, what I need is only to know the reason.