This seems not very common - from a quick check of images of similar sculptures available online (see list below, from museums or auctions), I found only one example in an auction in Köln (via Drouot)

https://www.drouotonline.com/l/15353995---stele-de-vishnu-pierre-noirc

My problem remains the precise reading/meaning of these two (genuine or added later?) inscriptions (which does not make sense to me yet, as far as I am able to read them).

Best wishes,

Christophe

https://commons.wikimedia.org/wiki/File:Vishnu_with_consorts,_India,_Pala_period,_12th_century_AD,_stone_-_Middlebury_College_Museum_of_Art_-_Middlebury,_VT_-_DSC08240.jpg

https://www.metmuseum.org/art/collection/search/38120

https://artmuseum.princeton.edu/collections/objects/28869

http://jameelcentre.ashmolean.org/collection/3/per_page/25/offset/0/sort_by/date/object/12482

https://searchthecollection.nga.gov.au/object?uniqueId=102840

https://www.alamyimages.fr/musee-national-de-l-inde-delhi-vishnu-11eme-siecle-a-d-pala-du-bengale-occidental-pierre-l-inde-image177655275.html

https://archaeologynewsnetwork.blogspot.com/2014/06/pala-period-vishnu-idol-unearthed.html

https://www.artcurial.com/en/node/1122459

https://www.bonhams.com/auctions/22316/lot/59/?category=list

https://www.bonhams.com/online_auctions/26903/lot/1251

https://www.bonhams.com/auctions/26589/lot/89/

https://www.auction.fr/_fr/lot/stele-of-vishnu-in-black-stone-pala-period-north-india-pala-period-ad-760-1142-8587681

https://www.auction.fr/_fr/lot/vishnu-stele-stein-bengalen-ost-indien-pala-11-12-jh-8959943

https://www.sothebys.com/en/buy/auction/2021/indian-himalayan-southeast-asian-works-of-art/a-sandstone-figure-of-vishnu-pala-period-11th-12th

https://www.sothebys.com/en/auctions/ecatalogue/2011/indian-southeast-asian-works-of-art-n08727/lot.16.html

https://www.bada.org/object/carved-black-stone-stele-vishnu