Merge pull request #29434 from frappe/mergify/bp/develop/pr-29404

fix: Previous document currency getting overridden (backport #29404)
diff --git a/erpnext/accounts/party.py b/erpnext/accounts/party.py
index 6b4b43d..c13bc23 100644
--- a/erpnext/accounts/party.py
+++ b/erpnext/accounts/party.py
@@ -58,7 +58,7 @@
 		frappe.throw(_("Not permitted for {0}").format(party), frappe.PermissionError)
 
 	party = frappe.get_doc(party_type, party)
-	currency = party.default_currency if party.get("default_currency") else get_company_currency(company)
+	currency = party.get("default_currency") or currency or get_company_currency(company)
 
 	party_address, shipping_address = set_address_details(party_details, party, party_type, doctype, company, party_address, company_address, shipping_address)
 	set_contact_details(party_details, party, party_type)