I have the theme block active on my site. What i want is on one theme there should be both the left and right block, where as on the other theme every thing should be in left block only. Is this possible?

Let's see if I understand.

You have 2 themes on your site, 1 which has the right and left columns and another only the left. And you would like that the theme that has only the left column to be displayed the blocks on both in this place, I am sure?

If this even what you want, you simply copy the loop of blocks of the right column of a theme for the left column of another theme, which is subsequently with both loops in the same column.

understand?

Any doubt that may have still ask here that we will respond

Regards

Thanks, but thats not what i want, sorry for not being clear.
What i mean is say there are two blocks, main menu and user menu. In the first theme i want user menu to appear in left column and main menu in right column, and in the second theme i want both user menu and main menu to appear in the left block.