[Q] Help with S4 Clone

Hello,

I bought an unlocked TMobile GSM S4 and it appears to be a clone. I've put down below the information I've observed so far.
I'd like help understanding which source of information would be correct, CPU-Z & Antutu, or the Genuine Galaxy App. And since the OS is halfbaked, is there a stock OS I should be looking for?

Any advice, suggestions, insights would be greatly appreciated!!!

Obserations:
1. OS is very possibly a custom
- Upon hard reset, there are no TMobile apps.
- Samsung app opens into a Korean counterpart store-type app
- Antutu and CPU-Z are pre-installed
- Calendar, FM Radio, and several other apps seem partially complete (empty spaces, tabs don't work)

2. Home screen pages: pages return after a restart (that is after I have already removed several pages and left just home page)

3. IMEI and S/N check out fine on several verification websites (e.g ucc.co.ug, etc); I can see mfr was Samsung, made in Vietname, production date and

warranty information all present (Could this all check out OK even with a clone?)

4. Antutu and CPU-Z Information (CPU-Z in parentheses if different from Antutu)
- Phone model: GT-i9500 (CPU-Z: GT-I9500 JA3GXX)
- CPU Hardware: Universal5410 (CPU-Z: Samsung Exynos Oct 5410 1.6)
- CPU Model: Quad Core ARMv7 Processor (CPU-Z: ARM Cortex-A15+ARM Cortex-A7, Cores = 4+4)
- Revision: CPU-Z: r2p3
- Core 0: 1001MHz
- Core 1: Stopped
- CPU Frequency: 250.0~1600 MHz
- Screen Resolution: 1080x1920
- CPU Vendor: Imagination Technologies
- GPU Renderer: PowerVR SGX 544MP
- Memory Size: 26705/30639MB
- Ram: 1254/1794
- Internal Storage: (CPU-Z: Total Ram: 1860, Available 260MB; Internal storage 8.92 GB, Available storage 7.83GB)
- Root Access: (CPU-Z: Yes)
- Android Version: 4.2.2
- Build Number: JDQ39.I9500XXUAMDL
- Kernal: Linux version 3.4.0 (rs@rs-ThinkStation-D30) (gcc version 4.6.x-google 20120106 (prerelease) (GCC) )#1 SMP PREEMPT Thu Apr 10 16:02:54 CST 2014
- Kernal Version: (CPU-Z: 3.4.5-526212 I9500XXUAMDL)
- Sensors (CPU-Z showing varied readings when phone is moved): light, orientation, magnetic, accelerometer, gyroscope, vector, gravity

5. Camera showing 13mp, but clicking sound when focusing. Picture quality not better than my Note2

5. 'Genuine Galaxy' App Readings (Formatted in app as Actual + Reference)
- Message: 'im afraid youre not using a galaxy S4'
- Model: GTI9500 (Reference GT-I9500)
- Device Brand: Samsung (Ref: Samsung)
- CPU Hardware: SMDK4X12 (Ref: Universal5410 (Exynos5410)
- CPU Model: ARM Processor Rev 0(V7l) (Ref: Same)
- CPU Cores: 2 (Ref: 4)
- CPU Frequency: 1001MHz (Ref: 1600MHz, 1800Mhz...)
- Total Ram: 469MB (Ref: 2GB)
- Total Rom: 950MB (Ref: 16GB, 32GB..)
- Screen Res: 960x540 (Ref:1920x1080)
- Camera: 8MP (Ref:13MP)
- Benchmark score: 12,500 (Antutu showi

Can't uninstall cpuz or antutu. There is only a disable option.
As for the service codes, I searched for the codes and this is what I have so far:

*#0*#
Sensors: only Accelerometer Sensor showing up
* #1234#
AP: I9500XXUAMDL
CSC: I9500OLBAMDK
*#12580*369# to check software and hardware information.
AP:I9500XXDLJ2
CP:I9500XXDLJ2
CSC:I9500OXADLJ2
RF CAL: 2013.4.25
HW REV: MP 1.300
*#0228# Battery status (ADC, RSSI reading)
NO RESPONSE
*#32489# Service mode
NO RESPONSE
*2767*4387264636# - show the product code
NO RESPONSE
*#0011# - Service Menu
NO RESPONSE

Seems very likely that it's a fake or clone. And the OS has so many glitches (empty calendar app, s memo etc..)

Thank you for assessment. Surely is a scam. It's there a way to install a better stock like Rom? And wouldn't a reinstall affect the cloned imei? Is installing a Rom on a cloned phone more challenging than a regular phone?