Hi Marta,
Yes! Unfortunately, you cannot link different blog posts with the same subtopic keyword. It would be difficult for a Search engine to crawl, analyse and rank your content and website for the same URL. So, it’s crucial to have a unique URL for each topic.
Like in the provided example, you can link both the topics that are Sales CRM and MKTG CRM to the same pillar page like CRS, but you cannot use the same target URL for both the contents. Furthermore, you can leverage HubSpot SEO tool to get an idea about other keywords that you can use for the respective title and link it with the respective pillar page.
Hope it helps! Moreover, if you want any assistance, don’t hesitate to contact us.