Q:

How do I run Spark jobs concurrently in the same AWS EMR cluster ? 

Is it possible to submit and run Spark jobs concurrently in the same AWS EMR cluster ?  If yes then could you please elaborate ? 

A:

You should use the tag --deploy-mode cluster that will allow you to deploy multiple executions to your cluster.  That will make yarn handle the resources and the queues for you. 
The full example:
spark-submit \
  --class org.apache.spark.examples. SparkPi \
  --master yarn \
  --deploy-mode cluster \  # can be client for client mode
  --executor-memory 20G \
  --num-executors 50 \
  /path/to/examples.jar \
  1000

More details here.