WD 2TB Gold WD2005FBYZ in RAID-1 Higher Performance due Cache MB management?

Us with professional technical background in electronics, we never make easy to be answered questions.

I did read that Enterprise class WD2005FBYZ in RAID-1, these outperform a single WD2005FBYZ at MB/s transfer.

According to my current experience with RAID-1 and with double WD Raptor 10.000 rpm 75GB of the year 2005, these HDD’s lose 7% when are in RAID-1 vs benchmarks with a single HDD.

My motherboard this is Gigabyte GA-Z87X-UD5H
10 SATA ports
Intel(R) Chipset SATA/PCIe RST Premium Controller
Service: iaStorAC
Device class: SCSI Adapter

Now I have two questions:
a) I am going to make a RAID-1 pair with

01YCBB3 this is classified as UASP (Serial ATA) = better handling of SCSI commands due USB 3.0 connection.
01YCBB2 this is classified as USB (Serial ATA) = not really compatible to latest edge of USB 3.0 standard.
Therefore should I freely assume that there is no negative performance impact at (Serial ATA) connection?

b) WD2005FBYZ this has 128MB of Cache, how is possible at RAID-1 to outperforms a single HDD?
Is there any technical innovation (not publicly spoken) this combing both HDD cache 128+128 so this combination to outperform the identical HDD when this run single?

I did extended web search for several weeks, Google this is empty of specific HDD benchmarks in RAID-1.
And this is a fault of WD marketing, which does not offer free samples to professional blogger, neither has an easy door so to be contacted.

Now I am forced acting as another Sherlock Holmes, so to discover the truth.

I have start to think this community be a true graveyard.

Neither incoming responses from WD employ.
Neither incoming responses from expert users.

I have electrician certification
I have Microsoft certification
And I do not have further time to waste with marketing claims.

Hi @Kiriakos-GR ,

Have you opened a Support Case? If not opened, for more information, please contact the WD Technical Support team for the best assistance and troubleshooting:

Myth busting time.
I am using for the past 48 hours my (fresh build) RAID-1 Array.
Both WD Gold 2TB onboard.

I am happy with their performance, 200 Mb/s with Crystal-Disk-Mark-8
And 135 Mb/s due Win OS diagnostic / command line / winsat diskformal

Those WD Gold replaced my pair of WD Raptor 75GB 10000 Rpm (year 2005) = 82000 hours of use.
I am pleased to see that WD Gold series does not have performance penalty when working at RAID-1 Array.
Old WD Raptor 75GB this were 15% slower at RAID-1, while as a single drive it did perform according to factory specification 70 Mb/s.