SQL User Advice Piwik / Joomla

I have recently created a Joomla 3 website which consists of one user (all privileges) and one database on my shared hosting account.

I’d now like to install Piwik analytics aswell (http://piwik.org/). What would be the best way of approaching this as regards users? Piwik requires one db user with all privileges.

Would I use the same user I have already set up for Joomla, or would I create a new user for the Piwik install. I’m not sure if it makes much difference, however if somebody could point me in the right direction I would be most grateful.

I would like to keep things as simple as possible because my shared hosting (BT) does not allow users to modify db user privileges - and my client wants to stay with BT. Therefore each time I set up a user I have to contact them and wait (up to) 48hours for a response.

I’m quite new to DBs so apologies for the naive question.