It looks to me as if they have done a 5-5-5 or a 5-6-5 bit level encoding to maximize the color capability within 16 bits. what this means is for lets say a 5-6-5 that the bit encoding would look like the below.
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| 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
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| red | green | blue |
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However in your case it also looks as if they swapped byte order meaning that yours based upon the order you gave could actually look as follows (bytes ordered as you show them):
| byte 0 | byte 1 |
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| 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
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| low green | blue | red | hi green |
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