Add a router between the switch and the problematic device, like so:

    +------+   
    |Device|
    +------+
(MAC Address: A)
       |
       |
    +------+
    |Switch|
    +------+
       |
       |
 (MAC Address: B)
    +------+                      +------------------+
    |Router|------(MAC Address: A)|Problematic device|
    +------+                      +------------------+

This way your problematic device will be on another L2 segment and won't collide with your other device.

Assuming you can't change the switch's configuration. Add a router between the switch and the problematic device, like so:

    +------+   
    |Device|
    +------+
(MAC Address: A)
       |
       |
    +------+
    |Switch|
    +------+
       |
       |
 (MAC Address: B)
    +------+                      +------------------+
    |Router|------(MAC Address: A)|Problematic device|
    +------+                      +------------------+

This way your problematic device will be on another L2 segment and won't collide with your other device.

Add a router between the switch and the problematic device, like so:

Switch---Router---Problematic device

This way your problematic device will be on another L2 segment and won't collide with your other device.

Add a router between the switch and the problematic device, like so:

    +------+   
    |Device|
    +------+
(MAC Address: A)
       |
       |
    +------+
    |Switch|
    +------+
       |
       |
 (MAC Address: B)
    +------+                      +------------------+
    |Router|------(MAC Address: A)|Problematic device|
    +------+                      +------------------+

This way your problematic device will be on another L2 segment and won't collide with your other device.