"I bought dance edtion 4 from Catoh.  It contains 2 styles, Dance Electro 9 and Techno Trance 13.  When I added the styles,I got duplication....turns out 2 styles in Basic_17 from MM17 are already named that but contain different content.  Even tho I got 2 names, the content is not different, so I renamed them to Dance Electro 9a and Techno Trance 13a and everything appears to be working fine....but that begs another question"

I am not from Magix but a user and like to clear some points other than "Detailed explanation is in order."

First Same name, different content....why is that?

Because you are not aware of soundpool and Magix Music software.

There are different Music Maker versions.

Such as Magix Music Maker, standard, premium or mx etc.

In standard version there are few soundpools if I am not wrong as in MMM 17 there are Five styles, HipHop, Rock, Techno, Dance and Chillout. But in the Premium of MMM 17 there will be more. What if you got MMM 17 and also bought Soundpool DVD 17 separately? there is a possibility it will contains sounds from MMM 17 Premium and could be more or less as it is not part of the Music Maker Basic folder.

If you got MMM 17 Premium version, it may contain following styles.

Breakbeat/Dubstep
Chillout
Dance / Electro
Deep House
Hip Hop / R'n'B
Jazz
Minimal
Movie Score
Rock /Alternative
Techno / Trance

(data taken from http://www.magix.info/us/soundpool-dvd-9-18-title-and-genres-revised.online-training.782381.html

Therefore, it is possible the similar styles in the MMM 17 Premium can also be found in the given below Magix software because it is Magix product and they got their own rules.

MAGIX Digital DJ 2
MAGIX Music Maker Soundtrack Edition
MAGIX Music Maker Hip Hop Edition 4
MAGIX Music Maker Dance Edition 4
MAGIX Music Maker Rock Edition 4
Music Maker Lethal Bizzle Edition

As you referred, two styles Dance Electro9 and Techno Trance 13 were similar styles included in the Basic_17 of MMM 17. It is possible, I wonder if you listen to those styles in Music Maker? In Music Maker under Sytyle it clearly shows the Vol number too.  On the Catooh website we can play MAGIX Music Maker Dance Edition 4  video before we place an order to avoid any confusion.

http://www.catooh.com/uk/sys/id/Katalog/area/mediaDetails/item_id/242628/

It is is normal that the Music Maker software Basic_17 folder got more styles than the MAGIX Music Maker Dance Edition 4. It got two styles as per Catooh website.

"Dance Edition 4 is 2 styles and 1.5GB in size...Wav files.    BAsic_17 is 12 styles and 350MB in size and is OGG Vorbis.....Why is there such a huge difference ?  Detailed explanation is in order.  Talk about more bang for the buck !!!Thanks"

Now the size and format difference. It is natural wav format files are larger in size because they are uncompressed and due to quality they are larger. While OGG/OGG vorbis is an another compressed audio format and smaller in file size. The OGG compression of audio varies in bit rate. it is open source and free that is why this format is also being used. But in quality non professional can not notice a big difference between Wav and Ogg quality but file size only.

Hope this answer will help you at some level.