Billing Terms Editor

[Neil night]

Using gnucash 2.4.11 windows, 2.4.7 on ubuntu oneiric writing to mysql 
database. All seems well, except for the billing terms editor.

Added:
due on receipt
net 14
net 30

So far, whenever I add a new vendor bill, select 'net 30' from the 
drop-down, a new entry in the billing terms editor is created for each 
invoice. So, if I enter 30 new vendor invoices, each time selecting 'net 
30' in the billing terms dropdown, I will end up with 30 new 'net 30' 
entries in the billing terms editor, none of which is deletable (error: 
term "net 30" is in use. you cannot delete it). And of course, the 
billing terms drop-down gets populated with all of these duplicate entries.

Oddly, the problem only seems to exist with 'net 30'