diff --git a/addons/web_editor/controllers/main.py b/addons/web_editor/controllers/main.py
index df43054847d..0b0806b3f39 100644
--- a/addons/web_editor/controllers/main.py
+++ b/addons/web_editor/controllers/main.py
@@ -34,6 +34,26 @@ DEFAULT_LIBRARY_ENDPOINT = 'https://media-api.odoo.com'
 DEFAULT_OLG_ENDPOINT = 'https://olg.api.odoo.com'
 
 
+def get_existing_attachment(IrAttachment, vals):
+    """
+    Check if an attachment already exists for the same vals. Return it if
+    so, None otherwise.
+    """
+    fields = dict(vals)
+    # Falsy res_id defaults to 0 on attachment creation.
+    fields['res_id'] = fields.get('res_id') or 0
+    raw, datas = fields.pop('raw', None), fields.pop('datas', None)
+    domain = [(field, '=', value) for field, value in fields.items()]
+    if fields.get('type') == 'url':
+        if 'url' not in fields:
+            return None
+        domain.append(('checksum', '=', False))
+    else:
+        if not (raw or datas):
+            return None
+        domain.append(('checksum', '=', IrAttachment._compute_checksum(raw or b64decode(datas))))
+    return IrAttachment.search(domain, limit=1) or None
+
 class Web_Editor(http.Controller):
     #------------------------------------------------------
     # convert font into picture
@@ -355,7 +375,8 @@ class Web_Editor(http.Controller):
             if not attachment_data['public']:
                 attachment.sudo().generate_access_token()
         else:
-            attachment = IrAttachment.create(attachment_data)
+            attachment = get_existing_attachment(IrAttachment, attachment_data) \
+                or IrAttachment.create(attachment_data)
 
         return attachment
 
@@ -530,7 +551,11 @@ class Web_Editor(http.Controller):
             fields['res_id'] = res_id
         if fields['mimetype'] == 'image/webp':
             fields['name'] = re.sub(r'\.(jpe?g|png)$', '.webp', fields['name'], flags=re.I)
-        attachment = attachment.copy(fields)
+        existing_attachment = get_existing_attachment(request.env['ir.attachment'], fields)
+        if existing_attachment and not existing_attachment.url:
+            attachment = existing_attachment
+        else:
+            attachment = attachment.copy(fields)
         if alt_data:
             for size, per_type in alt_data.items():
                 reference_id = attachment.id
diff --git a/addons/web_editor/static/src/components/media_dialog/file_selector.js b/addons/web_editor/static/src/components/media_dialog/file_selector.js
index 169173622ab..01465547da5 100644
--- a/addons/web_editor/static/src/components/media_dialog/file_selector.js
+++ b/addons/web_editor/static/src/components/media_dialog/file_selector.js
@@ -315,7 +315,7 @@ export class FileSelector extends Component {
     }
 
     async onUploaded(attachment) {
-        this.state.attachments = [attachment, ...this.state.attachments];
+        this.state.attachments = [attachment, ...this.state.attachments.filter(attach => attach.id !== attachment.id)];
         this.selectAttachment(attachment);
         if (!this.props.multiSelect) {
             await this.props.save();