Can I double up on this kit ???

Below is a scottish ale 60, as you can see it's a low abv, like 3.1%.

Can I simply double up on all the ingrediants and be OK???

Brew Schedule
5 gallon full boil

1lb Caramel 40L Steep 20 minutes at 155F
.25lb Caramel 120L Steep 20 minutes at 155F
.125lb Chocolate Malt Steep 20 minutes at 155F
3lbs Gold DME 60 minute boil
1oz Fuggle hops 60 minute boil
US-05 Dry Yeast Ferment cool 60-62F

You could.. but what would be the point? Just buy a kit that matches the beer you want to make. It seems idiotic to buy two kits when you could just get one with a higher gravity.

I got a good deal on 3 kits that are all the same which are in my posession so getting the higher gravity version is really not an option.

I was either going to double up two of them or simply add 1 lb extra DME to each batch to kick up the ABV%

Makes no difference to me if I make up 15 gallons or just 10 but was wondering if it was easy enough to just double up on 2 kits and roll on with it??

Yeah, the only problem I see with doubling up is that you'll also be doubling up on the specialty grains, and I don't think you'll need that. You can definitely add a little more extract to up the gravity, and if you wanted you could add a little more specialty grains, but with almost 1.5lb of crystal in the batch already, I don't think I'd go up to 3lb.

Are the grains crushed already? If not, I'd just plan on saving the grains from one batch for a future batch, then take that 3lb of extract and split it between the other two kits, giving you 4.5lb of extract in each batch. That should up the gravity a little without becoming too cloying from too much crystal. You could even split the hops between the two to help up the IBUs a little, but you'd have to plug that into a recipe to make sure you weren't getting too bitter for the style. I admittedly tend to like less crystal in general, so this is just what I would do.