Two BD-R discs had issues while burning or verifying with external BD drive

Before I start explaining, this is what ImgBurn says while checking the disc, again:

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ASUS SBW-06D5H-U E101 (USB)
Current Profile: BD-R

Disc Information:
Status: Complete
State of Last Session: Complete
Erasable: No
Sessions: 1
Sectors: 12.143.552
Size: 24.869.994.496 bytes
Time: 2698:36:02 (MM:SS:FF)
MID: RITEK-BR3-000
Supported Read Speeds: 6x
Current Read Speed: 2,5x - 6x

TOC Information:
Session 1... (LBA: 0)
-> Track 01 (Mode 1, LBA: 0 - 12143551)
-> LeadOut (LBA: 12143552)

Track Information:
Session 1...
-> Track 01 (LTSA: 0, LTS: 12143552, LRA: 12143551)

Disc Definition Structure:
Certified: No
Scanned: No
Manufacturers Name: PIONEER
Additional ID: SBW-06D5H-U
Serial Number: BADL255379WL

BD Disc Information:
Disc ID: RITEK-BR3-000
Disc Type: BD-R
Disc Size: 120 mm
Disc Class: 0
Disc Version: 1
Disc Time Stamp: 10/2010
Number of Layers: 1
Layer Type: Writable
DVD Layer Present: No
CD Layer Present: No
Channel Bit Length: 74.50 nm (25 GB Per Layer)
Push-Pull Polarity: Positive
Recorded Mark Polarity: HTL
BCA Present: Yes
Maximum Transfer Rate: Not Specified
First PAA of Data Zone: 131.072
Last PAA of Data Zone: 1.658.494

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Yesterday I burned a 25 GB BD-R filling 99% of data (24.869.928.960 bytes, total). I noticed the writing was sucessfully, but while verifying (and I do verify all discs after), ImgBurn returned the L-EC Uncorrectable Error while checking one of the files. Just one. ImgBurn continued the ckecking after that, and completed that task.

It seems the disc was burned 100% OK, but 1 of the 249 files had the MD5 hash changed. That's right, 249 files were burned total, 248 of them repeated the same HASH compared to my SSD.

1 didn't.

I used a program called MD5Summer, to create hashes from all of them. From SSD and BD-R.

After more/less 40 minutes, it did while checking this Ritek BD-R, then I repeated the same process with the folders, stored in my SSD.

This site compared the contents of both texts: https://www.diffchecker.com

It told me these hashes (digital fingerprints) are different:

BD-R:

d37d912a9952c34024977afce372b94f *MOVIE.mkv

SSD:

4e33f33f67936bfeddb5362bb938936c *MOVIE.mkv

That particular MKV has 3.34 GB size, 6 subtitles, 3 audio tracks, HEVC video...

And when I open from the BD-R, don't notice anything different (unless I need to watch 100% of the content, while also switching between tracks). But it IS different, since the hash changed.

The question is:

- What went wrong here, and should I assume this MKV is the same as the one stored in my SSD, despite the hash change? Or I need to do another backup from that single file?

Another Ritek BD-R I am having a problem with. Probably that area of the disc is damaged?

The other I had an issue spent more than 30 minutes "writing lead-in", and was stuck in that step. Do I need to discard this BD-R disc? I had to interrupt the writing, but ImgBurn says the media is empty.

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P.S. I was able to determine if the file was OK. It isn't, and I already discarded.

- Simply copy all contents from the BD-R into your SSD, again. If it fails, it's damaged.

All were fine, except for this affected MKV. So it's safe to assume the burning went OK 99%, except for that 1% related to that Matroska.

Also, after carefully looking into the disc surface, I believe I noticed either a small scratch which probably account for that problem, or some sort of disc surface anomaly, likely during manufacturing. I doubt this was caused by the external drive or ImgBurn, since other discs were fine during burning and checking. Or the fact I used 99%. This isn't the first coaster I am looking at... not the 1st time it happened, sadly.