I love both bags, because I have a thing for red bags -- it's such a great alternative to black, reds almost always go with everything. However, if I were to choose, since you have a black Venetia, you should sell the pomegranate one. This way you'll have two different bag shapes (satchel vs. shoulder bag) to complement outfits. Unless you have a VERY strong preference/attachment for the Venetia over the Blake (ie. you adore Venetia and feel so-so towards Blake), I'd sell the Venetia.
Although if I weren't on a bit of a purse ban, I'd say sell the Blake so I could buy it (hee hee)... just kidding! I'd still tell you to sell the pomegranate Venetia.