Once you file your rectification request online then you will be getting a message that your rectification return is submitted and you will be allowed to withdraw it within 7 days.
Once you submit your rectification request, you may file it again after withdrawing the same. Without withdrawing you cannot file your rectification request again since it will be under process.
Once it is processed and you get an unsatisfied reply then you may file your request again.
If your return is selected for any review/scrutiny by your Assessing Office then you cannot file your rectification request since it will be blocked for that.