Turns out they have been heard before, according to GrungeReport.net.
New film to feature never-before-heard Layne Staley tracks

Paste reports: Grassroots, a Seattle-centric film from director Stephen Gyllenhaal, will feature two never-before-heard songs from deceased Alice in Chains frontman Layne Staley. The film stars Jason Biggs as an alt-weekly music critic who suddenly decides to campaign for a highly competitive spot on the Seattle City Council.