diff --git a/instance_selector/static/instance_selector/instance_selector.css b/instance_selector/static/instance_selector/instance_selector.css
index b1def01..755fef0 100644
--- a/instance_selector/static/instance_selector/instance_selector.css
+++ b/instance_selector/static/instance_selector/instance_selector.css
@@ -6,11 +6,6 @@
     display: none;
 }
 
-/* Hide the add button */
-.is-instance-selector-embed .w-header .right {
-    display: none;
-}
-
 /* Override wagtail styles [smaller screens] to make sure the title appears in line with the rows */
 @media (max-width: 50em) {
     .is-instance-selector-embed .w-header.w-header--with-padding,
diff --git a/instance_selector/static/instance_selector/instance_selector_embed.js b/instance_selector/static/instance_selector/instance_selector_embed.js
index b10d064..9936d47 100644
--- a/instance_selector/static/instance_selector/instance_selector_embed.js
+++ b/instance_selector/static/instance_selector/instance_selector_embed.js
@@ -4,10 +4,20 @@
         ? window.parent.location.pathname.indexOf('/instance-selector/') !== -1
         : false;
 
-    const SESSION_STORAGE_EMBED_KEY = 'INSTANCE_SELECTOR_EMBED_ID';
+    const SESSION_STORAGE_EMBED_KEY_PREFIX = 'INSTANCE_SELECTOR_EMBED_ID';
 
     if (IS_INSTANCE_SELECTOR_EMBED) {
         const HASH_EMBED_ID = window.location.hash.split('#instance_selector_embed_id:')[1];
+
+        if (HASH_EMBED_ID && !window.name) {
+            // Give this specific frame a stable, unique identity so its
+            // sessionStorage key can't collide with any other (nested or
+            // sibling) instance-selector frame in the same tab.
+            window.name = SESSION_STORAGE_EMBED_KEY_PREFIX + ':' + HASH_EMBED_ID + ':' + Math.random().toString(36).slice(2);
+        }
+
+        const SESSION_STORAGE_EMBED_KEY = SESSION_STORAGE_EMBED_KEY_PREFIX + ':' + (window.name || 'default');
+
         // Persist embed id across page loads (allows clicking on filters, searching, etc)
         const SESSION_EMBED_ID = sessionStorage.getItem(SESSION_STORAGE_EMBED_KEY);
         if (HASH_EMBED_ID) {
@@ -56,7 +66,7 @@
             const success_messages = $('.messages .success');
             success_messages.each(function() {
                 const success_message = $(this);
-                
+
                 const buttons = success_message.find('.buttons a');
                 buttons.each(function() {
                     const button = $(this);
@@ -66,7 +76,7 @@
                         const data = get_data_from_url(url);
                         if (data) {
                             const select_button = $(`
-                                <a 
+                                <a
                                     class="button button-small button-secondary instance-selector__success-message__select-button"
                                     data-object-pk-for-debugging="${data.object_pk}"
                                 >Select</a>
diff --git a/instance_selector/static/instance_selector/instance_selector_widget.js b/instance_selector/static/instance_selector/instance_selector_widget.js
index a3f856e..ed4878a 100644
--- a/instance_selector/static/instance_selector/instance_selector_widget.js
+++ b/instance_selector/static/instance_selector/instance_selector_widget.js
@@ -33,6 +33,21 @@ function create_instance_selector_widget(opts) {
         opts.embed_url = opts.embed_url.replace(/__prefix__/g, index);
     }
     const widget_root = $('#' + opts.widget_id);
+
+    // Inside StreamField blocks this function is called twice for the same
+    // widget: once directly by the telepath widget definition
+    // (instance_selector_telepath.js, which needs the widget API back
+    // synchronously) and again by the Stimulus `instance-selector`
+    // controller's connect(), which fires because the widget's root element
+    // also carries `data-controller="instance-selector"`. Without a guard,
+    // both calls bind their own click handler on the trigger button, so a
+    // single click opens two stacked modal dialogs. Cache the widget API on
+    // the root element so the second call is a no-op.
+    const existing_widget_api = widget_root.data('instanceSelectorWidgetApi');
+    if (existing_widget_api) {
+        return existing_widget_api;
+    }
+
     const field_input = $('#' + opts.input_id);
     const display_edit_link = widget_root.find('.js-instance-selector-widget-display-edit-link');
     const display_markup_wrap = widget_root.find('.js-instance-selector-widget-display-wrap');
@@ -68,7 +83,7 @@ function create_instance_selector_widget(opts) {
                             Close
                         </button>
                         <div class="modal-body instance-selector-widget-modal__body">
-                            <iframe class="instance-selector-widget-modal__embed" src="${opts.embed_url}" frameborder="0"></iframe>                        
+                            <iframe class="instance-selector-widget-modal__embed" src="${opts.embed_url}" frameborder="0"></iframe>
                         </div>
                     </div>
                 </div>
@@ -173,5 +188,6 @@ function create_instance_selector_widget(opts) {
             trigger_button.focus();
         },
     }
+    widget_root.data('instanceSelectorWidgetApi', widget_api);
     return widget_api;
 }