The dual spectrum leds have a lot of green light in them and as far as i know this is useless to plants.
Here is a link to one of the best suppliers of led components i have found,these are very powerful yet cheap leds and they come in all the colours that you need.
Buy some white,red and blue ones and a light bar a few resistors a couple of 12volt power packs and your away with a more powerful led light than you can buy from anyone
Prolight Power LEDs 5 Watt, LED Shop - portofrei - LED1.de ®