Trouble Extending Over 2 Displays from My MacBook Pro

There were three different 2020 MacBook Pro models. (16,2 16,3 17,1)

see > Identify your MacBook Pro model - Apple Support

The 16,2 and 16,3 models both supported two external 4K displays up to 4096 x 2304 resolution.

Both external displays can not be connected to the ThinkPad Docking Station.

One must be connected directly to a different MacBook Pro port.

The 16,2 > MacBook Pro (13-inch, 2020, Four Thunderbolt 3 ports) - Technical Specifications - Apple Support

Video Support 

Simultaneously supports full native resolution on the built-in display at millions of colors and: 

• One external 6K display with 6016-by-3384 resolution at 60Hz at over a billion colors, or
• One external 5K display with 5120-by-2880 resolution at 60Hz at over a billion colors, or
• Up to two external 4K displays with 4096-by-2304 resolution at 60Hz at millions of colors

Thunderbolt 3 digital video output 

• Native DisplayPort output over USB‑C
• VGA, HDMI, DVI, and Thunderbolt 2 output supported using adapters (sold separately)

The 16,3 > MacBook Pro (13-inch, 2020, Two Thunderbolt 3 ports) - Technical Specifications - Apple Support

Video Support

Simultaneously supports full native resolution on the built-in display at millions of colors and:

• One external 5K display with 5120-by-2880 resolution at 60Hz at over a billion colors, or
• Up to two external 4K displays with 4096-by-2304 resolution at 60Hz at millions of colors

Thunderbolt 3 digital video output

• Native DisplayPort output over USB‑C
• VGA, HDMI, DVI, and Thunderbolt 2 output supported using adapters (sold separately)

The 17,1 model only supports one external display up to 6K.

The 17,1 > MacBook Pro (13-inch, M1, 2020) - Technical Specifications - Apple Support

Display Support

Simultaneously supports full native resolution on the built-in display at millions of colors and:

• One external display with up to 6K resolution at 60Hz

Thunderbolt 3 digital video output

• Native DisplayPort output over USB-C
• VGA, HDMI, DVI, and Thunderbolt 2 output supported using adapters (sold separately)

The issue you're experiencing is due to the fact that MacBooks do not support MST (Multi-Stream Transport). Therefore, when using the ThinkPad docking station, you can only extend to two identical screens, which is the situation you've described.

You need to check what kind of chip your MacBook Pro has. Since you mentioned it's a 13-inch MacBook Pro from 2020, it's likely equipped with an M1, M2, or M3 chip. These chips can only extend to multiple displays if you use a dock that comes with its own driver. such as:https://www.amazon.com/dp/B0D9JTD9PW

I hope this clarifies the issue and helps you find a solution. Thank you!

To support TWO displays on one cable out of your Mac, the Port, the cable, and the first device (Dock or Display) Must ALL be genuine Thunderbolt.

USB has only half as many data pathways, and the MAC does not support two displays over USB.

Send that Dock back to Windows-land, never to return.

The 13" 2020 MacBook Pro can only natively support two monitors total, either the internal display and one external display, or perhaps two external displays if you are running with the lid closed though I've seen varying reports on that issue. Also, I believe that supporting two external displays require a dock that supports Thunderbolt, though I'm not sure about that, and your ThinkPad dock probably doesn't support ThunderBolt. Someone else here will probably confirm or refute on both statements.

BTW, you posted in the iMac Pro forum, the Community forum for a now-discontinued desktop system. If you don't get further help here try posting in the MacBook Pro forum.

Regards.