There is no limit to the number of e-Mandates that can be set up for an account.
Related Question
How does ENACH work?
What is the prerequisite for me to register at ENACH mandate?
What is ENACH Mandate?
What will happen if my bank account balance is insufficient?
How can I turn off the recurring payment through ENACH?
How many mandates can I register through a single bank account?
There is no limit to the number of e-Mandates that can be set up for an account.