Kuky no one says that the MiG-29S(9-13S) cannot engage two targets - what we are saying is that the MiG-29(9-12 and 9-13) cannot.
Anyway, the first of your quotes is so full of errors that its not really worth using as reference - designations are flying all over the place and are for the most part wrong.
The weapons control system(WCS) for the 9-12 and 9-13 is called SUV-29 and includes the N019 "Rubin" radar. This is sometimes refered to as "RLPK-29", which is an abbreviation that IIRC translates to something like "Radio Location and Aiming Complex - 29", which in turn simply means....radar for the MiG-29 :) . This is what is simulated in Lock-on.
The WCS of the 9-13S is called SUV-29S(surprise) and involves the N019M "Topaz" radar. It has a modified SNP mode that can prioritise two targets, which can be engaged in succession with R-77 missiles directly from SNP. In order to cope with the increased processing required for this, the radar was upgraded with a more powerful main processor(possibly "borrowed" from the more advanced N010 "Zhuk")
It is true that there is also a more "obscure" 9-12S with the Topaz radar - i.e. the "non-fatback" 9-12 airframe. IIRC this is the version called MiG-29SD by MIG, which was exported to Malaysia where it entered service as the "MiG-29N". This variant also has a "bolt-on" IFR probe, but no ECM(Vekkinho).
However, there is no such thing as "S-29", "NO-019M", "N-109" or "N-019/3A ZHUK" :).
"Zhuk" has *nothing* to do with the N019 - it is a name Phasatron-NIIR allocated for an entirely new advanced radar design similar to the F-18's APG-65. The first set was the N010 "Zhuk", which was designed for the MiG-29M(9-15) and MiG-29K(9-31) multirole fighters. It had a planar slotted array antenna and a more powerful processor - it could track 10 targets in TWS(like the N019), "stack" up to 4 for engagement and simultaneously engage 2 with the R-77, which it(unlike the N019) was tailored to use. It also had air-to-surface modes supporting radar guided anti-ship missiles(such as the X-31A). This radar was also made in a version for the Su-27(-33 etc) called "Zhuk-27", which differed from the MiG-29 version merely by having a larger antenna(960 mm diameter) - i.e. NIIR's alternative to NIIPs N011.
Later NIIR made upgraded versions of these retaining the planar slotted array antennas- namely the Zhuk-M currently offered with the Indian MiG-29K/KUB(9-41/9-47) and MiG-29SMT2 upgrade, while the Zhuk-MS with a larger antenna was installed in the Su-27KUB prototype. These also come in versions with fixed passive phased array antannas; Zhuk-MF and Zhuk-MFS respectively. Finally there is the latest incarnation called Zhuk-A which is an active phased array(AESA) currently installed in the MiG-35 prototype.
Now to return to the topic (:D) - I would agree that the MiG-29S in the sim is not correctly depicted. Either it should:
a)...be "downgraded" to the 9-13 version - i.e. same airframe and retaining the internal Gardeniya jammer, but have the R-77 removed from its arsenal or...
b). ..be modified to allow launch of the R-77 directly from SNP(i.e. without automatically switching to STT) and for a second target to be "bugged" and engaged while continiuing to guide the first launched missile.
But I am sure you can see which of the two options is the easiest to implement :D - not least since there AFAIK isn't much in the way of documentation about exactly how the SNP mode of the N019M works and how it is displayed on HUD/HDD.