The package presents two similar, but not identical, sounding vocals. In the announcement on the official VOCALOID Facebook page, it was stated that anon represents "dere" (sweet) and kanon represents "tsun" (prim). The two traits spell out "Tsundere" when put together.
The packaged version of these voicebanks include over 200 uncompressed .wav files with phrases such as "Clap your hands", "Yo!", and "Hoooooo!!".
Vocal traits as noted:
Their ranges overlap each other and have similar tones, resulting in the vocals being relatively good for harmonization.
Though they have a 20BPM difference between each other, both share a 80 BPM tempo range, meaning that they can both can handle the majority of the same genres. However, the slight difference means a few genres can be handled better by one girl than the other.
Their vocals fit in a wide range of genres but excel at Rock and Pop in particular.
They are only the 3rd example of a "multiple character" and the second example of a "duo" or "twin" release. They are considered the first true "twins" within the Vocaloid software in addition. This is a rarity among Vocaloid as most multi-voicebank releases contain voicebanks intended for 1 character only.
Software issues as noted:
The tone of the two vocals are the same, so the versatility of the product is less than other duo Vocaloids.
Since they are separate characters and not the same one, they were not given the ability to XSY with each other in VOCALOID4, so importing them will not open this function for them. They share this issue with ZOLA PROJECT who also cannot XSY their 3 vocals.
There was a issue with the vocal types of the two girls because they sounded similar to past voicebanks.
This was not a fault of the developers, singers or voicebanks but rather the existing recording situation. At the time, the method of recording samples until VOCALOID3 made vocals Japanese vocals easier to use, but resulted in the vocals being indistinct at times. As a result by the end of VOCALOID3 vocals were struggling to stand out from each other. The result was many common vocal types began to emerge which the two girls fell into.