Yup.
Many glass artisans do it routinely. Glass kilns with top elements are
unsuitable for stack firing because the top elements cause the highest
layer to be warmer than all other layers. Ceramic kilns with side
elements only will distribute the heat evenly and permit multi-level
firings. Here's a glass artist that uses a tall ceramic kiln to fire
as many as 6 layers at a time.
http://www.thegardengallery.ca/

Some glass kilns, with both top and side elements, permit the top
elements to be turned down or turned off to permit stack firing.

Dennis Brady

DeBrady Glassworks
http://www.debrady.com
Victorian Art Glass
http://www.victorianartglass.biz
Glass Campus
http://www.Glass Campus