It's very hard to tell without your seeing the content of Q and your code what is going on. But my speculation is that Q has two rows with duplicate values and the row name of one is 5175488 and the other is 51754881.
And a further speculation is the when the data.frame Q was built it using rbind to combine two or more data.frames to make Q
Here is an example of what happens with you combine two data.frames the have rows with matching names. Some of the row names end up with numbers appended to keep all row names unique. You can't build a data.frame with row names that are not unique so rbind "fixes up" the row names as needed so that they do not clash.
In any case this is one of the reasons for including a reprex in your question so that the person who tries to answer it doesn't have to speculate a lot and build demo code from scratch.
tbl <-tibble::tribble(~a, ~b, ~c,
1,2,3,
1,2,3,
1,3,4,
2,7, 9,
1,6,3,
2, 8,2)
class(tbl) <- c("data.frame")
row.names(tbl) <- c("a", "b", "c", "d", "e", "f")
rbind(tbl, tbl)
#> a b c
#> a 1 2 3
#> b 1 2 3
#> c 1 3 4
#> d 2 7 9
#> e 1 6 3
#> f 2 8 2
#> a1 1 2 3
#> b1 1 2 3
#> c1 1 3 4
#> d1 2 7 9
#> e1 1 6 3
#> f1 2 8 2
Created on 2018-03-12 by the reprex package (v0.2.0).