A recent question in r/Emailmarketing describes a familiar ecommerce leak: a shopper submits a product-page popup, receives a welcome discount, then visits the homepage and submits a second popup for another code. It looks like a form-frequency problem, but it is really an offer-eligibility problem.

The cleanest Klaviyo setup is to make both forms feed one primary email list, then configure both forms to target only people who are not already email subscribers. Klaviyo’s own guidance for tiered signup offers recommends targeting forms to the appropriate audience and excluding existing subscribers. Once a visitor submits either form and becomes identifiable as a subscriber, the other welcome form should no longer be eligible to display. (help.klaviyo.com)

Use one welcome list, not two competing welcome programs

It is tempting to give the general popup and the product-specific popup separate lists, segments, and flows. That adds operational complexity and creates more opportunities for a person to qualify twice.

Instead, send both forms to the same main marketing list and trigger a single welcome flow from being added to that list. Klaviyo supports list-triggered flows specifically for sending automations when someone joins a list. A profile already on that list should not be treated as a brand-new list addition again just because it encounters another form. (help.klaviyo.com)

This approach also follows Klaviyo’s broader list-management advice: keep a main list for a channel, then use profile data and segments to understand how people subscribed rather than multiplying lists for every acquisition source. (help.klaviyo.com)

The practical build looks like this:

  1. Connect both forms to the same email list.
  2. In each form’s Targeting & behavior settings, show it to new visitors or exclude existing email subscribers.
  3. Keep the product form restricted to its relevant product URL, while the general form remains homepage-only.
  4. Turn on a single welcome flow from the shared list.
  5. Use a conditional split in that flow if the product-page signup deserves different copy, products, or a different incentive.

Klaviyo’s form settings let marketers control audience targeting, URL targeting, display timing, frequency, and priority from the form editor. (help.klaviyo.com)

Track source—but do not rely on a profile property as the lock

A hidden field is useful for recording where a subscriber came from. For example, the product form can write signup_source = product_popup, while the homepage form writes signup_source = general_popup. Klaviyo supports collecting profile properties through hidden form fields, and those properties can be used for segmentation and flow personalization. (help.klaviyo.com)

That data is valuable: it tells you which popup acquired the subscriber and lets the welcome flow tailor its first message. But it should be treated as attribution, not the main safeguard against duplicate codes.

Why? If a visitor can submit the second form, its hidden-field value can overwrite the first form’s value. Klaviyo explicitly notes that an existing profile property is overwritten when a new hidden field submits the same property. (help.klaviyo.com) A property updated later inside a flow is even less suitable as a display gate, because the form decision may happen before that automation step is processed.

The better gate is subscriber status: the first successful signup makes the visitor ineligible for the other acquisition offer.

Turn on collision prevention as a backup, not the primary fix

Klaviyo now has a built-in collision-prevention setting under the Sign-up Forms settings gear. It can prevent multiple popup, flyout, and full-page forms from appearing at once, or limit visitors to one form per session. (help.klaviyo.com)

Enable it. In this scenario, “show only one form per session” is a sensible extra layer because it stops the homepage popup from immediately following the product popup during the same visit.

But collision prevention alone is not enough. It is session-based experience control, not durable offer governance. It does not cover embedded or custom-triggered forms, and it cannot stop a returning visitor, another browser, or a shopper using a new email address from trying again. (help.klaviyo.com)

Protect the discount at the checkout level too

Finally, use unique codes rather than a shared static coupon whenever possible. Klaviyo distinguishes static codes, which can be shared broadly, from unique codes assigned to individual recipients. (help.klaviyo.com) Unique codes will not by themselves prevent one person from being issued two codes, but they reduce casual code sharing and make redemption analysis clearer.

The durable playbook is simple: one list, one welcome-entry point, subscriber exclusion on both forms, source tracking via hidden fields, and collision prevention for a cleaner onsite experience. That turns two popups from competing discount machines into two paths into the same intentional welcome journey.

The scenario in this article was prompted by a question posted by u/Responsible-Bar32 in r/Emailmarketing; no substantive community replies were available in the supplied discussion.