The Aire Street site was applied for in 2006 and it took until 2009 to sign a 106 agreement for the approval.
This has now been applied for renewal without any changes to the "Grand" scheme.
The bridge Street site was approved in 2006 and was renewed in 2010 minus the Hotel part of the development.
There is obviously an interest from some company or companies to locate a "Supermarket" at this side of the town.
The location (Aire Street or WR) may come down to the need for such a development (Which everyone seems to agree there is) and which location is best in terms of planning, the cost and speed of delivery to the mystery retailer.
If I was the retailer I know which site I would be pushing for.
IMHO!