There are some POIs that have the same Wikidata code, but this can't happen.
Here a list of all the POI IDs with this problem:
SELECT wikidata_code, GROUP_CONCAT(poi_ID) FROM poi WHERE wikidata_code <> '' GROUP BY wikidata_code HAVING COUNT(*) > 1 ORDER BY COUNT(*) DESC;
+---------------+----------------------+```
| wikidata_code | GROUP_CONCAT(poi_ID) |SELECT wikidata_code, GROUP_CONCAT(poi_ID) FROM poi WHERE wikidata_code <> '' GROUP BY wikidata_code HAVING COUNT(*) > 1 ORDER BY COUNT(*) DESC;
+---------------+----------------------+```
| wikidata_code | GROUP_CONCAT(poi_ID) |
| Q1145261 | 16605,15656 |
| Q17798 | 14315,14651 |
| Q178813 | 13469,11651 |
| Q18040 | 14286,14659 |
| Q18356 | 14264,14637 |
| Q18365 | 14267,14644 |
| Q18368 | 14643,14268 |
| Q18416884 | 10661,10770 |
| Q18755063 | 8108,7944 |
| Q1903 | 12755,16045 |
| Q1916826 | 15043,16018 |
| Q19840 | 16180,7271 |
| Q19846 | 7273,16300 |
| Q20099 | 14341,14638 |
| Q20109 | 14344,14649 |
| Q20191 | 14650,14367 |
| Q20251 | 14383,14648 |
| Q2034331 | 15070,15268 |
| Q2047639 | 8348,8439 |
| Q20478 | 14890,14372 |
| Q20494 | 15028,14896 |
| Q2077168 | 11427,11282 |
| Q21013539 | 16579,16553 |
| Q21192547 | 14485,14489 |
| Q21192550 | 9563,10943 |
| Q21552096 | 9266,9265 |
| Q21552273 | 9280,9204 |
| Q224172 | 14350,14902 |
| Q23291 | 14697,14288 |
| Q2506967 | 11857,10965 |
| Q254139 | 14455,14561 |
| Q266604 | 14544,14463 |
| Q266794 | 14554,14457 |
| Q266941 | 14460,14550 |
| Q266975 | 14547,14449 |
| Q268067 | 14470,14257 |
| Q268995 | 14320,14471 |
| Q269516 | 14404,14474 |
| Q269823 | 14482,14445 |
| Q270032 | 14466,14560 |
| Q270189 | 14571,14456 |
| Q270320 | 14979,14556 |
| Q270328 | 15015,14564 |
| Q270492 | 14441,14526 |
| Q270548 | 14512,15014 |
| Q270613 | 14462,14527 |
| Q270782 | 14454,14506 |
| Q271152 | 14511,14451 |
| Q271236 | 14517,14446 |
| Q271358 | 14444,14528 |
| Q28001134 | 7041,7065 |
| Q2967848 | 9398,7825 |
| Q2968191 | 8829,14751 |
| Q30159213 | 12387,12642 |
| Q3328396 | 9366,15991 |
| Q3361323 | 10637,10944 |
| Q3364763 | 13187,13299 |
| Q34805 | 14708,14994 |
| Q35082 | 14340,14754 |
| Q35226 | 14718,14226 |
| Q358729 | 14696,13328 |
| Q3649109 | 10617,8766 |
| Q3657503 | 15804,16428 |
| Q3662426 | 11652,10052 |
| Q3662456 | 9648,9610 |
| Q3718646 | 15404,8912 |
| Q3757770 | 15285,9066 |
| Q3763803 | 9232,9230 |
| Q376739 | 8897,9080 |
| Q3785099 | 14073,14180 |
| Q3867520 | 9025,8925 |
| Q3867716 | 9135,16096 |
| Q3867764 | 8047,8009 |
| Q3867831 | 9173,9172 |
| Q3867851 | 8263,8262 |
| Q3867963 | 8790,9037 |
| Q3867973 | 9024,9005 |
| Q3868051 | 8677,9075 |
| Q3868253 | 8885,8886 |
| Q3868400 | 7994,7993 |
| Q3868487 | 9022,9151 |
| Q3886621 | 15832,16466 |
| Q3886642 | 15944,16441 |
| Q3889575 | 15277,16554 |
| Q3889659 | 10800,10632 |
| Q3890190 | 15254,15264 |
| Q3890261 | 15287,15286 |
| Q3890698 | 13602,13612 |
| Q3892388 | 14518,14686 |
| Q3895631 | 13206,14591 |
| Q3895646 | 13216,16177 |
| Q3895647 | 14666,13217 |
| Q3895726 | 13180,14083 |
| Q3934723 | 11336,11345 |
| Q3936898 | 10762,10555 |
| Q3951389 | 10456,10245 |
| Q4011905 | 6985,6977 |
| Q47467390 | 15045,13962 |
| Q50119 | 15132,15133 |
| Q54087650 | 8914,8525 |
| Q54874186 | 9058,9059 |
| Q55354223 | 8003,8004 |
| Q55354232 | 10057,7972 |
| Q55370383 | 8884,16161 |
| Q55372377 | 14812,8944 |
| Q55375790 | 8823,8840 |
| Q55379362 | 8237,8238 |
| Q55391578 | 9733,9732 |
| Q55686292 | 11359,11360 |
| Q55832719 | 11241,10842 |
| Q574879 | 13490,13491 |
| Q58844 | 13273,14184 |
| Q606494 | 7891,7856 |
| Q635414 | 14116,13324 |
| Q867361 | 7208,13318 |
+---------------+----------------------+
115 rows in set (0.02 sec)