How to fix "Duplicate, Google chose different canonical than user"

I do not how to differentiate the content of two similar URLs

[guarriman3]

I've got a directory with 20,000 products ('Acme Turbo 1', 'Acme Special 12', etc.)

For each one of the products, I've got:
*) mysite_com/where-to-buy/acme-turbo-1: It links several shops where you can buy the product
- H1 + Title: "Buy Acme Turbo 1"
- H2: "List of the shops where you can buy Acme Turbo 1"
- links
- (no more stuff)

*) mysite_com/where-to-repair/acme-turbo-1: It links several factories where you can repair the product
- H1 + Title: "Repair Acme Turbo 1"
- H2: "List of the factories where you can buy Acme Turbo 1"
- (no more stuff)

In Google Search Console, I've got thousands of "Duplicate, Google chose different canonical than user" messages, where Google warns me:
- User-declared canonical: mysite_com/where-to-buy/acme-turbo-1
- Google-selected canonical: mysite_com/where-to-repair/acme-turbo-1

I offer valuable, unique content for users (the useful links). But, obviously, Google considers that the two pages have very similar content, but I do not how to differentiate both them. Some ideas:
- Changing the texts in H1 and title?: "Buy Acme Turbo 1" and "Find where to repair your Acme Turbo 1"
- Changing texts in H2?
- Deleting the H2 tag and converting it into 'p'?

Any tip is welcome, thank you.

[aristotle]

- User-declared canonical: mysite_com/where-to-buy/acme-turbo-1

Can you provide us with the exact canonical tags that you put on each of the two pages.

[lucy24]

the exact canonical tags

... using “example.com” as the sitename.

[guarriman3]

Sorry, I was not clear with the description of the issue in Google Search Console.

In Google Search Console, I've got thousands of "Duplicate, Google chose different canonical than user" messages, where Google warns me. As an example, this would be the message for the URL 'https://example.com/where-to-buy/acme-turbo-1'
- User-declared canonical: https://example.com/where-to-buy/acme-turbo-1
- Google-selected canonical: https://example.com/where-to-repair/acme-turbo-1

This is, I declare --as the canonical URL-- the same URL of the page. However, Google estimates that the valid canonical URL is another one (with very similar contents for the same product, and very similar URL).

[aristotle]

Well you still haven't provided the canonical tag that you put into the head of each page.
They should have the form:
<link rel="canonical" href="https://example.com/where-to-buy/acme-turbo-1">
A self-referencing canonical tag declares itself as the canonical. If you want to declare a different page as canonical, you would use that page's URL

[lucy24]

Well you still haven't provided the canonical tag that you put into the head of each page

Lacking evidence to the contrary, we are allowed to assume that G### is reporting accurately--if only because OP would have said so if G were talking through their hat. (As has been known to happen.) Page lists itself as canonical; G chooses to treat a different page as canonical for the same content.

The questions then become:
#1 Just how similar are these two types of pages--“where to buy” and “where to repair”--and what is it about the “repair” version that G finds more attractive?
#2 And, conversely: just how different are these two types of pages, and is it necessary or appropriate to maintain them as separate pages?

[guarriman3]

@lucy24, thank you very much for your nice answer.

#1 Just how similar are these two types of pages--“where to buy” and “where to repair”--and what is it about the “repair” version that G finds more attractive?

They are pretty similar. As I commented firstly, they share pretty similar H1s and titles, with "Acme Turbo 1" in them. And the two H2 texts are also quite similar, both have 20-30 words, most of them identical, and including "Acme Turbo 1" as well. There is no more text in each webpage but the title, the H1, the H2 and the links.

And the 'repair' version, in this case, offers more links than the 'buy' version (20 vs 3). And it may be the reason that leads G to find it more attractive.

#2 And, conversely: just how different are these two types of pages, and is it necessary or appropriate to maintain them as separate pages?

Good question. Yes, I could merge them, but users search explicitly "Buy X" and "Repair X". Most of them are #1 ranked.

I do not know if the solution can be the merge of the URLs or the 'enrichment' of the texts (to tell G that they are two different pages). I can write 3 paragraphs with 'p' (instead of the 'H2' short text), or I can include into these directory pages more stuff of each business. This is, instead of just linking 'where to buy' with the name of the business, I can show the address in the directory.

[tangor]

Good question. Yes, I could merge them, but users search explicitly "Buy X" and "Repair X". Most of them are #1 ranked.

In which case the consolidated page hits both parameters and nothing is lost, other than one more page on which to hand advertisements. The side benefit is that BOTH presentations (as one) will get eyeballs all, instead of just the "repair" side of things.

Sometimes less is more...