I disagree with the suggestion in the Expert Review article that it is a "problem" that AP's/Routers offer the same SSID in both wavebands. There is no right or wrong way to do this, it's a choice with each option having virtues and vices.
A "dual band" AP/Router is like having two Wi-Fi AP/Routers in the same box, one AP/Router serving each radio waveband (known as the 2.4GHz and 5GHz wavebands.)
Not all Wi-Fi protocols are available in each waveband. Mandated by standards, B/G are 2.4GHz only, A/AC are 5GHz only, N is available in both wavebands, though it's not mandatory to support both - some older "dual band" routers only availed N in "one or the other" but not both.
The is more "frequency spectrum" available in the 5GHz waveband which (put grossly over-simply) means you have better chance of faster rates with 5GHz waveband/protocols: With the right client/router mix: And good radio signalling conditions: And a whole load of other caveats: Including line of sight.
It is the client devices that decide if/when to "roam" between AP's with the same SSID not "the system." It is Big Wi-Fi Myth Number 2 that clients are always "hunting for the best signal" - in fact this is not the case. Some will hang on to a "working" link until it's pretty grotty before considering hunting for something better.
So, if you make the SSID's (and passphrase etc.) the same, then your clients may automatically swap between the two depending on how their designers choose to make them. With dissimilar SSID's the client will never swap until it completely looses connection and "starts from scratch" as if you'd just turned it on.
However, with dissimilar SSID's, you can "choose your band" from the client as by definition you are presented with a choice of AP's, but you'll never roam.
With same SSID, you won't be given a choice of AP - the equipment (or OS) designer effectively "designs in" the decision for you. But you might get roaming between bands automatically.
So, which way to go is a value judgement you need to make for yourself.
In a big deployment (with hundreds of AP's) I avail same in both and let the clients decide. Most people wouldn't want the bother of making the choice for themselves. But in a SOHO you may prefer to distribute clients between the two - say fast closer clients in 5GHz, slower distant clients in 2.4GHz.
Some clients (typically laptops) have some controls in the NIC drivers that offer a degree of control. For example, some will let you "favour" a particular band and/or protocol. Some offer "harder" options that absolutely disable particular protocols. For example if I make my laptop "AC" only, it forces use of 5GHz even if 2.4GHz SSID is available (and "stronger") with the same SSID. Though some NIC's offer no control at all.
Of course many devices (phones for example) don't offer any controls.
It's also worth noting that not all clients support both wavebands - there's a lot of 2.4GHz only kit out there.