Why both the strands of DNA do not act as template for RNA synthesis ?

Explanation

Both the DNA strands cannot in transcription because that will produce two types of proteins, one with correct sequence of amino acids and the other with reverse sequence of amino acids. Further if two complementary RNAs are produced simultaneously, they would have a tendency to form double stranded RNA resulting in non-translation of coded information into proteins. The whole exercise of transcription would then appear futile.