It is generally not a recommended procedure. The abrasion of carpet on carpet will cause both layers to wear prematurely.
Certain types of glue down carpet can be installed over existing glue down carpet. Check the manufactures installation instructions. I do agree that installing stretch in carpet over existing stretch in carpet is not a good idea.
do you need a power stretcher to install a carpet or can you ues a knee kicker
form_title= Cheap Carpet form_header= Install cheap carpet in your home. What is the square footage of your home?*= _  Do you want to install padding?*= () Yes () No What color carpet do you want to install?*= _  Do you need to remove old carpet?*= () Yes () No
form_title= Shaw Carpet from_header= Install carpet in your home. Do you need to remove existing carpet?*= () Yes () No Do you want to install stain resistant carpet?*= () Yes () No What color do you want the carpet?*= _ 
We decided to do a carpet design in the playroom using carpet squares. What is the best way to install carpet squares on a cement floor?
form_title= Carpet for Stairs form_header= Install carpet on your stairs with help from the pros. Do you need to remove old carpet?*= () Yes () No What color carpet would you like to install?*= _  What is your budget for carpet?*= _ 
Carpet kickers, or knee kickers, are used to install a fitted carpet. They help to install the carpet more tightly and flat than would be possible otherwise.
You probably have the kind that clamps down on the edge of the carpet. It started out as a V. the bottom part is nailed down, the edge of the carpet is inserted and the top half clamped down to hold it. There are hooks on the bottom half that grab the carpet. To remove it, pry up the top half, hold back the carpet and pull up the strip.
Empire carpet and flooring is a good company that will install quality carpet for a good price. Their phone number is 1-800-588-3200 and their website is www.empiretoday.com
There is no reason not to install carpet over wooden floors. If you want to learn how to do this, visit the DIYNetwork website. Once on the page, type "How to install carpet over hardwood flooring" into the search field at the top of the page and press enter to bring up the information.
Yes you can.
By the foot, carpet is about $2 & tile is about $5.