laying over existing laminate flooring

Just want to know if it is ok to lay a new laminate floor on top of an existing one.
The floor is concrete base and I was going to rip up the old laminate one but then thought that it might work as extra insulation.
The room is a garage convertion that is used as a family/playroom which can get quite cool if heating is off,especially in the cooler months.
Would appreciate any advice. Thanks.
p.s. would I have to lay membrane over old floor before laying new one?
Thanks

The question to ask is: If the existing flooring is in such condition as to need replacing, why should it be good enough to act as a base for new flooring?

The existing flooring is fine, in good condition.I am decorating the room as it hasnt been done since we moved in 9 years ago and the flooring has been down since then.
The children are older now but at the time we put down the cheapest laminate as the kids would be playing and knocking lumps out of it but it has lasted well!
As I am doing it up into a family room I am changing the flooring also and just want to know if the existing laminate can be kept as extra insulation.

Hi
It is ok to do this but it is not the best idea in the world as your doors may need to be took off and planed down and there is a small possibility that the floor may sweat if there is any damp at all if it is for insulation you may be better to remove the old laminate and lay a 6mm insulation board.

Paddy1077.
Thanks for the reply,I will take your advice on board.Many thanks,net64