That is expected result, as I mentioned above:
Toolset Reapitable Field Groups are based on one-to-many relationships, each item of Reapitable Field Groups is also a single post.
So one "Tour" posts can connected to multiple "repeating field group" posts, as a result, when you query "repeating field group" posts, and display their parent "Tour" post 's information, it will output parent "Tour" post multiple times.
As a workaround, you can try these:
1) Create a post view "2020-tour-date":
- Query "dates-tour-leaders" post
- Filter by:
Select items with field:
start-date is a number between DATE(01, 01, 2020), DATE(01, 01, 2021)
- in section "Loop Editor", within Views loop <wpv-loop> ... </wpv-loop>, display it's parent tour post IDs only, as below:
[wpv-item index=1][wpv-post-id item="@dates-tour-leaders.parent"][wpv-item index=other], [wpv-post-id item="@dates-tour-leaders.parent"]
- Enable option "Disable the wrapping DIV around the View"
2) Create a post view "2020-tour-posts":
- Query "tour" post
- filter by: Post ID filter
Include only posts with IDs set by the View shortcode attribute "ids" eg. [wpv-view name="view-name" ids="1"]
- within Views loop, display "tour" post information
3) Create a wordpress page "2020-tours"
Display above post view's shortcode(step 2), with "ids" attribute of post view "2020-tour-date", for example:
[wpv-view name='2020-tour-posts' ids='[wpv-view name="2020-tour-date"]']
More help:
https://toolset.com/documentation/user-guides/passing-arguments-to-views/#controlling-the-filter-with-shortcode-attributes