Depends a lot from the material and skills you have, sometimes even if you have practice with glassing the wetout isnt easy because of the material.
Pretty much with two layers at once you need to double the attention, for me works better to drape both and get references on the cloth using tape or a colored thread, cut the overlapping areas and so on. Then roll the second layer onto something (i use a pvc tube that runs on two lines on each side of the piece im working on), wet the first quickly paying attention that there are no dry spots but not bothering much with the eccess resin as long as its not a blob, and put the second layer on right away, the fact that i have references on the cloth and that i can unroll it along the keel permits me to drape it on without probems since i have to do that alone, with an helper you could put the second layer on more easily without rolling it up first. If the cloth could move i have no problems tacking it where necessary, just on top of the second layer. After the second layer is on i squegee (or use an old brush with the bristles cut in half so its quite stiff, it depends on which area im working, the brush is useful to tap onto the glass to help the wetting too, i do most of the work with it, squegee its for places where i need more pressure) while its dry, so it absorbs resin from the first layer. At this point even with a slow resin it still can be gelling, so the faster you work the better it is, and thats why the material is important, if its really light cloth that tends to float and you have difficulties wetting a single layer then two at once can be a waste of time.
The last thing is to mix more resin and finishing saturating the second layer.

Practice on a scrap first, not a small piece, try to get a fairly large piece that will give you a better idea of what the problems are and remember to not overload the scrap with resin because on the hull you will be trying to get lot of mileage out of each batch and dont cheat yourself lifting the cloth from one end to let bubbles out because on something big like a kayak you cant do that. If your cloth wets very easily and you see that trapped air isnt an issue at all then go on with both cloth at once wetting them out all together, from the middle towards the edges to avoid bubbles.

A small vacuum bagging system its the best way with multiple layers, if you know you will use fiberglass more than once for several applications then it could be worth to look into it, it doesnt need to be top of the line stuff so its not much a matter of money rather than a little more time and work to rig it up.

: Just so I am clear...

: When putting on more than just 1 layer of glass, are you waiting until the
: first layer epoxy has hardened but is tacky prior to adding the second
: layer or are you laying both layers at the same time then applying the
: epoxy to both at once???

: If you can do it either way, which is best?

: Thanks, Tim