Super Mario Land: GB, 3DS VC
Super Mario World: Wii U VC, GBA
Super Mario 64: Wii VC, Switch
Super Mario Sunshine: GCN, Switch
Super Mario Galaxy: Wii, Switch
Stardew Valley: Switch, PS4
The Walking Dead Seasons 1-3+ Michonne: Windows, PS4
The Walking Dead Season 4: Switch, PS4

Those are all the ones I can think of right now, but I'm pretty sure there's more.

Gta v on 360, ps4 and pc

Minecraft on pc and xbox

Ff15 on ps4 and xbox gamepass

Soon to be super mario bowser fury on switch and wii u. Assasin creed 3 on wii u and xbox one

And many more games from wii u and switch.. I can't remember their names

I'm sure I'm missing a bunch...

Ico (PS2, PS3)
Shadow of the Colossus (PS2, PS3)
Jak and Daxter (PS2, PS4)
Resident Evil 1, 2, 3 (PS1, PS3)
Resident Evil 4 (GCN, Wii)
Castlevania: Symphony of the Night (PS1, X360)
Okami (PS2, Wii)
Metal Gear Solid (PS1, PS3)
The Legend of Zelda (NES, GCN)
Zelda II (NES, GCN)
A Link to the Past (SNES, GBA)
Link's Awakening (GBC, 3DS)
Ocarina of Time (N64, GCN)
Majora's Mask (N64, GCN)
Wind Waker (GCN, WiiU)
Twilight Princess (GCN, Wii, WiiU)
Breath of the Wild (WiiU, NS)
Ikaruga (X360, Switch)
Guacamelee! (PS3, Switch)
Guacamelee! 2 (PS4, Switch)

hoo boy, I don't even wanna think about all the different copies of games I have on different consoles.

Final Fantasy is one that I definitely love and is all over the place. FFX I have:

On Ps2
On PSVita
On PS4 Physical
On PS4 Digital
On Switch Physical
On Switch Digital
On Steam

I'll have to make a complete list, but there are tonnes of games I have just on PS4 and/or Switch that I have physically and digitally (one for the sake of collecting, one for Convenience, one for portability, one for fidelity).

Stardew Valley /Xbox One/Switch/Steam
Sonic Generations /Xbox 360/Steam
Sonic Adventure /Gamecube/Steam
Gears 5 /Xbox One/Steam
Divinity Original Sin /Xbox One/Steam
Prey /Xbox One/ Steam
Fallout 4/ Xbox One/Steam
Conan Exiles /Xbox One/Steam
Mass Effect /Xbox 360/Steam
Mass Effect 2/ Xbox 360/Steam
Sacred 2 /Xbox 360/Steam
Two Worlds /Xbox 360/Steam
Two Worlds 2/Xbox 360/ Steam
Battlefield 4 /Xbox One/Steam
The Witcher 3 /Xbox One/ Steam
Outward /Xbox One/ Steam
Okami HD/ Xbox One/ Steam
Vampyr /Xbox One/ Steam
Ryse Son of Rome /Xbox One/ Steam
Bouncy Bob /Switch/Steam
No Thing /Switch/Steam

Way too many to count. At least half of my GOG games catalogue is games that I already have either on a disc or on floppy discs, and some even on both. Also, GOG had a thing where if you had a Steam version of some game, you got the GOG version for free, further bolstering the catalogue.

As for console games (not counting Switch online):

The Legend of Zelda (NES/Virtual Console)
The Legend of Zelda II (NES/GBA/VC)
Super Mario Bros 2 (NES/GBA/VC)
Super Mario Bros 3 (NES/VC)
Teenage Mutant Ninja Turtles (NES/VC)
Super Mario World (SNES/VC)
Street fighter II Turbo (SNES/VC)
Secret of Mana (SNES/VC/Switch)
Secret of Evermore (SNES/VC)
Donkey Kong Country 1-3 (SNES/VC)
Wind Waker (Gamecube/Wii U)
Freedom Planet (PC/Wii U)

I probably forgot some games that I have at least double on consoles, but that's all that comes to my mind right now.

Yeah if you start counting all the doubles from bundles and sales the list becomes huge. I didn't count free versions, Portal 2 for example already came with a Steam code on the ps3 version. I played both, each had its pros and cons (looked better on PC, ran more stable on PS3). I also played Burnout Paradise again on PC, got it from a sale bundle.

Then there are the countless doubles from ps+ (although you don't technically own those) and free generational updates which blend in to BC nowadays. Oh and you had all those PS3 Vita cross buys as well as cross buys between PC and 360.

And I guess, Tetris is the winner when it comes to owning the most copies of the 'same game'. 

Several. But the only ones that matters in this realm are my 2 deluxe edition copies of Corpse Party:Blood Drive on the Vita.

Nin gostathar gwaith bán a gellathar!

Minecraft on PS4, iPad and another Tablet.

Too many to, count, I have hundreds of games double or triple... some games even in more versions.

Many for different systems (even excluding crossbuy games for PS3, PS4, Vita)... often the PC version for best quality + a handheld or mobile version for "on the go".

Sometimes the physical + digital version for the same system (very often for old retail PC games, where I'm too lazy to get the disc out of its box and the Steam/GOG versions are cheap).

Also many duplicate digital PC games for different PC game launchers (first version on Steam or GOG, then additional versions due to Epic gifts, monthly Amazon Prime games, GOG Connect and many game bundles).

I also have the Collector's box of "Defender of the Crown" including the versions for C64, CPC, ZX Spectrum, Apple2, NES, Amiga, Atari ST, DOS, Mac, "Amiga Extended", Amiga CDTV, Amiga CD 32 and CD-i... oh, and an Android port of the Amiga version for my phone. 

And since someone mentioned movies... I bought my favorite movie "Terminator 2" around ten times (beginning with crappy VHS and "Letterbox" DVD versions) and eventually kept six of them: