fixed article duplication typos (#16216)

lib/pure/collections/sequtils.nim

@@ -1101,7 +1101,7 @@ macro mapLiterals*(constructor, op: untyped;
 iterator items*[T](xs: iterator: T): T =
   ## iterates over each element yielded by a closure iterator. This may
   ## not seem particularly useful on its own, but this allows closure
-  ## iterators to be used by the the mapIt, filterIt, allIt, anyIt, etc.
+  ## iterators to be used by the mapIt, filterIt, allIt, anyIt, etc.
   ## templates.
   for x in xs():
     yield x

lib/pure/math.nim

@@ -622,7 +622,7 @@ when not defined(js): # C
       ## Note: Not available for JS backend.
     proc gamma*(x: float32): float32 {.importc: "tgammaf", header: "<math.h>".}
     proc gamma*(x: float64): float64 {.importc: "tgamma", header: "<math.h>".}
-      ## Computes the the `gamma function <https://en.wikipedia.org/wiki/Gamma_function>`_ for ``x``.
+      ## Computes the `gamma function <https://en.wikipedia.org/wiki/Gamma_function>`_ for ``x``.
       ##
       ## Note: Not available for JS backend.
       ##

lib/pure/streams.nim

@@ -346,7 +346,7 @@ proc write*[T](s: Stream, x: T) =
   writeData(s, unsafeAddr(x), sizeof(x))
 
 proc write*(s: Stream, x: string) =
-  ## Writes the string `x` to the the stream `s`. No length field or
+  ## Writes the string `x` to the stream `s`. No length field or
   ## terminating zero is written.
   runnableExamples:
     var strm = newStringStream("")