Solution
The reason this problem happens may be because they are bound to the incorrect driver. However, there is a workaround for this issue. Customer will need to create a udev rule for this issue. Please take a look at the steps below for the detail.
1. Launch 𝚃𝚎𝚛𝚖𝚒𝚗𝚊𝚕.
2. Enter command 𝚜𝚞𝚍𝚘 -𝚒
(Purpose is to get permission).
3. Enter command 𝚗𝚊𝚗𝚘 /𝚎𝚝𝚌/𝚞𝚍𝚎𝚟/𝚛𝚞𝚕𝚎𝚜.𝚍/𝟾0-𝚗𝚒𝚍𝚛𝚒𝚟𝚎𝚛𝚜.𝚛𝚞𝚕𝚎𝚜(Purpose is to create rule for binding drivers).
4. Paste the following text, where
ATTR{device} is the
ProductNum of the PCI card.

5. Click 𝚂𝚊𝚟𝚎 𝚊𝚗𝚍 𝙴𝚡𝚒𝚝.
6. Reboot the system.
After rebooting, PCI-6503 and PCI-6509 is able to be recognized normally as shown in Figure 2.

Figure 2. PCI-6503 and PCI-6509 are recognized as Dev1 and Dev2 respectively.