Thank you for raising this concern. We fixed the issue and the new destination tags are now entirely random numbers. Old destination tags will still work for a while.
If you should experience any problems with them, please contact our support at:
https://www.bitstamp.net/support/How long is the old one can be used? I can see that the deposit dt in textbox is different from the button that the button is still showing the old one. What's more, when i tried to send btc to the new one in ripple client, it just send back and charged some fee.
Will we get a notice when the change begin?