Let's take a look at the Souizen vs BAG.
Souizen: $???
Dual: No
Damage: 8
Spread: 0.06
Freeze: 0.12
Fire Rate: 0.25
Reload Freeze: 0.40-0.3
Auto: Yes
Clip: 12
Perk: Suitcase Attachment
Battle Automatic Rifle (BAG): $???
Dual: No
Damage: 8
Spread: 0.06
Freeze: 0.12
Fire Rate: 0.25
Reload Freeze: 0.40-0.3
Auto: Yes
Clip: 12
Perk: Laser Attachment
You can see that their stats are practically the same. Are they considered a full on cloned weapon? Not exactly.
Souizen is held on the character's right hand. This greatly changes the combat situation. In spar matches, the Souizen has the advantage at the top right area and the lower left area in spar. Since most weapons are held on the character's left side, Souizen users that are placed in their advantageous spots are proven deadly. Then again, if the Souizen user is at the top left and the lower right, their opponent now has the slight advantage over them. Using the Souizen means placing yourself in the proper positions for easier spar wins. So now that you were focused on getting the bottom area, you are now focused on getting the bottom left area. While at the top, you now have to worry about getting the top right area.
The BAG is a less complicated version of Souizen. The BAG is held on the character's left hand. This is the standard position for most guns. Rather than worrying about which position you need to be in, you can use the BAG like most other guns. So if your opponent is using a left handed weapon, there is not much of an advantage or disadvantage on which area you are in. Resulting a bit more balanced spar (despite you are using a powerful spar weapon) What you are left worrying about is enemies at the bottom area, and reloading. The BAG also has a different perk than the Souizen. While it does not affect all enemies, some sparrers have complained that the laser attachment makes BAG's bullets harder to see. While the advantage is making the BAG's bullets harder to see, it also makes it easier to see which direction the BAG is facing and where the bullet's line of direction it is headed.