Fetish, Street Grimoire, 212. I did a research but only found houserules and 4th rules. Maybe I missed something new.
Lets take a look at the text, I'm snipping here for space and so we're not just ripping off the full text. Emphasis with font modifiers is added:
[...]Such spells have to be learned specifically with the fetish, meaning that a character would have to learn a spell twice if he wants to cast it both with and without a fetish. An alchemist needs 1 dram of radical reagents to make the fetish functional for magical use. A magician casting a fetish spell [...]
So, the text in the book never mentions the magician needing to perform anything to attune themselves to a fetish. The
bold text indicates that the radical reagent is part of the materials to create the fetish, not part of being able to make use of it. I took a look, and this is probably in need of some errata, because a dram of radical reagents is worth 4,500 nuyen (according to Shadow Spells). So that just doesn't fit with any of the pricing, period. For now, I would say ignore the bit about radical reagents...
As I was saying, the text never mentions anything about the magician bonding to the fetish, but as the first
italicized section mentions, you must learn a spell specifically with the fetish. And it is later (in the other italicized part) referred to as the "fetish spell" meaning that it is about learning a spell as a fetish spell, and potentially means that if you lose the fetish you could have to relearn the spell entirely. None of these things mention a limit of how many spells can be learned with a specific fetish. So purely by RAW, you don't need more than one fetish. As you mentioned there are a lot of houserules out there, and references back to 4th edition. I won't go into those details, but purely from what is written there isn't a
stated requirement.
And yes, if you want to be able to cast the spell with or without the fetish, you have to learn it twice (5 karma each time), as stated in the
underlined statement. Since you weren't quoting the book, and that wasn't stated like a question, I wasn't sure if that part was confusing you or not...