Millisecond Forums

Hi all,
I'm trying to code a task where two stimuli appear on the screen at the same time, one on the left and one on the right. Because a picture can appear on the left or the right, I have defined two types of <picture>'s to determine position on the screen and these draw from the same pool of items. 
In my trials, though, some pictures are appearing more than once, even though I have used the noreplace function - I think because two types of pictures are each separately not replacing from the pool of items rather than the pool of items not replacing across both locations. Is there any way to fix this?
I'm new to Inquisit and so have used a pretty basic (probably not the best) way of coding - I haven't used list elements, just defined my pictures and then used trials with /stimulustimes to determine what appears when.

Any help would be much appreciated! Thanks very much.

Jodie