Multiple enrolment email messages with Hikashop

I am integrating Joomdle with Hikashop and I have nearly everything working.
Here is the scenario: Added one Moodle course to the cart. I am using a coupon so that the item is free, so there is no payment plugin involved.
Once I have hit the final Submit button during Hikashop checkout, the website is grinding away while I receive three separate (but identical) enrollment emails, equally spaced within a roughly two-minute period. Then I receive the order creation email from Hikashop. I do get enrolled in the course, but something is amiss.
Any thoughts?

I turned on error reporting and I am seeing some warnings, which repeat twice and involve a foreach loop, so I am suspecting this might cause three email messages to be sent. Here are the messages:

Strict Standards: Only variables should be assigned by reference in {path to site}/plugins/system/joomdlehikashopstartdate/joomdlehikashopstartdate.php on line 38
Strict Standards: Only variables should be assigned by reference in {path to site}/plugins/system/joomdlehikashopstartdate/joomdlehikashopstartdate.php on line 47
Warning: Invalid argument supplied for foreach() in {path to site}/plugins/system/joomdlehikashopstartdate/joomdlehikashopstartdate.php on line 105

And then these three messages repeat exactly.

I've also attached a text file with the errors in the server log.

Sorry, I had to scrub private info out of the server log. Here it is again:

Hi.

How many Joomdle-Hikashop plugins have you installed/enabled? Please list them. Only one of type system (the one doing enrolment) must be enabled (normal one, start date, or groups)

Aha! Well, that might be it. I have five installed and enabled:

Hikashop profile
Hiakshop Integration
System - Joomdlehikashop
System - Joomdlehikashop with groups
System - Joomdlehikashop with enrol start date

So, I only need the first three of these, correct?

And if so, that means that an installation can only have one method? So it's not possible to have some products that can use one method and another use a different one? Or would there never be a case where that would be necessary.

Sorry for all the questions, but aside from the multiple email problem, this has made for a pretty slick system and I'm already thinking about ways to make it even better.

No problem at all with the questions.

You are right, for normal use only those 3 are needed.

As you say, you cannot mix methods at this moment. Groups and start date plugins were developed for special cases for some clients, and I don't think they are used in many installations.

Thanks for the clarification. I think I just installed (and enabled) all of the Hikashop plugins at once.

I'm still getting an error at the end of processing an order, but I seems to be a Hikashop problem because it happens on orders where there is no Moodle class. Thanks again for your help.