Next time I have a question, I think I'm going to ask it in as confusing and incomplete manner as possible... because that ALWAYS gets a great response here
(Some response is snarky. But, hey, that sometimes happens anyway... regardless how clearly you ask).
As I understand it, you are asking if you "need" a second camera... I am not entirely sure if you are thinking of an upgrade, or actually using two cameras or are thinking of having a 2nd camera on hand in case your 1st one breaks.
Working with the info we've gleaned from your post (which doesn't actually ask a question, BTW), the only possible answer is... "It depends".
We can't offer opinions "Yes" or "No", because we just don't have enough info to make a reasonable judgment.
Do you feel the camera you've got isn't adequately accomplishing something you'd like it to be able to do?
Google tells me the "RX10M4" is some sort of Sony. And dpreview.com has a review of a DCS RX10 IV. Is that the same camera? If so, it's a bridge camera... non-interchangeable lens, extreme zoom range (equivalent to 24mm to 600mm on full frame/film) using a CX format (1") 20MP sensor. (The actual focal length of the Zeiss zoom lens is 8.8mm to 220mm, but these are "exaggerated" by the smaller size sensor. Regardless, it's a 25X zoom, which is pretty extreme!)
But what do you want to do with your camera? Are you shooting sports? Wildlife? Portraits? Landscapes? Family photos? Close-ups/macro? Or ???
And what do you do or want to be able to do with your images? Only share them digitally online? Make small prints up to around 8x10"? Make large prints 13x19", 16x24" or bigger?
Are you shooting as a hobby? Or are you wanting to "go pro"?
A DSLR or MILC (mirrorless interchangeable lens camera) would give you more versatility, being able to change lenses for different situations. Prime lenses (instead of zooms) or much less extreme range zooms will generally make for better image quality too (less distortions, better sharpness and fine detail, better controlled chromatic aberration and more). DSLR and MILC also use larger sensors that make for better image quality and/or higher resolution. CX/1" sensors like the DCS RX10 IV uses measures 13.2mm x 8.8mm. This gives a total area of 116 square millimeters... which means a sensor producing a 20 million pixel image has over 172,000 individual pixels per square mm. Compare that to a so-called APS-C sensor commonly used in DSLRs and MILC, which are about 23.6mm x 15.6mm,with total area of roughly 368 mm sq. (there's actually some slight variation... between 330 and 370 mm sq.)... where a 24MP image means around 65,000 individual pixel sites per mm sq. Or, there are "full frame" DSLR and MILC with 36mm x 24mm sensors, about 864 mm sq., where a 30MP image results in around 35,000 individual pixel sites per mm sq.
Less crowded sensor with larger pixel sites make for greater fine detail in images, as well as less "noise" in images made at higher ISOs (caused in large part by heat gain and "crosstalk" between crowded pixels). The larger sensors allow higher ISOs to be used, so that you can keep shooting even in lower light conditions.
But we don't know from your question if any of these things are a concern to you.... or even if you are just asking if a 2nd camera would be a good idea to have with you, in case the first one fails for some reason. Or if you have another reason for thinking you might need a 2nd camera...
Just for example, I shoot a lot of sports with a couple identical 20MP APS-C DSLRs. I use two so that I can set them up with different lenses... such as a 100-400mm on one an a 24-70mm on the other... then can switch back and forth quickly, as needed. This also means less need to change lenses, since I often have to shoot in dusty conditions. I also have two more APS-C cameras as backups, just in case something happens.
For other types of photography, I use a 21MP full frame DSLR. It's great for landscape and architecture. I also like using it for portraits and macro photography.
Those DSLRs and many of the lenses I use on them are fairly big and heavy. For travel and more casual uses I've considered getting a smaller, lighter MILC and a few lenses to use on it. (A MILC would also allow me to use some vintage lenses I have in my collection, via simple adapters. Right now I have to use those on film cameras, then scan the film if I want to work with it digitally.) Right now I have a couple old non-interchangeable lens, compact "point n shoot" digital that I tuck into a backpack pocket. Image quality of those and other things are quite limited, though. Your much newer bridge camera is bound to be more versatile than my P&S, but less capable than my DSLRs.
But these are examples of what works for me... gear that meets my photography needs. It's probably quite different for you. But we would need to know more, before we could make any suggestions.