If you're seeing more than one overlay dialogue (notification bar, lightbox, toaster, or slide-out) appearing on the same page at the same time, this article explains why it happens and what you can do about it.
How BlueConic decides which dialogue to show
BlueConic enforces a single-overlay rule per page view: when multiple overlay dialogues are eligible for the same visitor and page, only one is shown. The dialogue with the highest priority (set on the When tab) wins. Dialogues with the same priority rotate on a round-robin basis across page views.
This rule, however, has two important limits:
It applies per page view, not per visit. A second overlay can appear after the first is closed, or when the visitor navigates to a new page.
It does not prevent a page-load overlay and an event-triggered overlay from both appearing on the same page. These two types can fire together because they are evaluated separately — the single-overlay rule only governs dialogues competing in the same trigger category.
How to prevent dialogues from stacking
There is currently no built-in setting that blocks a second overlay from appearing while another one is already open. Use the following strategies to reduce or eliminate stacking in practice:
1. Set priority on the When tab
Assign a higher priority to the dialogue that should take precedence when multiple page-load overlays compete for the same visitor and page. Lower-priority dialogues will be suppressed for that page view.
2. Use mutually exclusive Where and Who targeting
Make competing dialogues ineligible for the same visitors or pages at the same time. For example, if Dialogue A targets visitors who have already seen a promotion, exclude that segment from Dialogue B's Who rules. If two bars target different site sections, confirm their Where tab URL rules don't overlap.
3. Avoid pairing page-load and event-triggered overlays on the same pages
If you have a notification bar that fires on page load and a separate bar that fires on a user action (such as a button click), both can appear simultaneously on the same page. If stacking is a problem, consider whether the event-triggered bar can be scoped to pages where the page-load bar is not active, or consolidate both into a single dialogue.
4. Use frequency limits and "do not show again" settings
Set frequency caps and "do not show after interaction" rules (on the When tab) so that a dialogue shown once does not remain eligible on subsequent visits or pages during the same session. This reduces the chance of a second overlay appearing shortly after the first.
Requesting simultaneous-overlay suppression
Preventing more than one overlay from displaying at the same time — regardless of trigger type — is not currently supported natively in BlueConic. If this is important to your use case, contact support to log a feature request.
Still seeing unexpected stacking?
If dialogues are still stacking after applying the steps above, check the following:
Verify that the dialogues sharing the same pages have different priority values — same-priority dialogues rotate rather than suppress each other.
Confirm your Where tab URL rules are not inadvertently overlapping. Use the simulator to test which dialogues are eligible for a specific URL and visitor profile.
Check whether any of the stacking dialogues are event-triggered. If so, review whether the triggering event (such as a click or scroll threshold) can be restricted to pages where the page-load bar is inactive.
If the issue is with a specific visitor or segment, test using a fresh browser profile (without cookies) and the BlueConic simulator to reproduce the eligibility conditions.