Remove Duplicates From Col.A And Merge Col.B

i have a wordlist containing about 0.5 Million words in col.A and Millions of meanings in Col.B. Now in Col. A there are many duplicates. I would like to make one cell of all duplicates in col.A and put their meanings together in B with seperator ";". Its very important that there are no duplicates in Col. B.

For example:
Col. A Col.B
w1 m1;m2;m3
w1 m1;m2;m5
w2 m23;m24
w2 m50

Now after running the macro the list should look like:

Col.A Col.B
w1 m1;m2;m3;m5
w2 m23;m24;m50

The words in col. A are alphabetically ordered and all the duplicates are followed by each other.

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