diff --git a/lib/yargs-parser.ts b/lib/yargs-parser.ts
index 48a2d0f2..ad18a53f 100644
--- a/lib/yargs-parser.ts
+++ b/lib/yargs-parser.ts
@@ -620,13 +620,13 @@ export class YargsParser {
         if (typeof val === 'string') val = val === 'true'
       }
 
-      let value = Array.isArray(val)
+      let value: string | number | boolean | typeof incrementMarker | Array<string | number | null | undefined> | null | undefined = Array.isArray(val)
         ? val.map(function (v) { return maybeCoerceNumber(key, v) })
         : maybeCoerceNumber(key, val)
 
       // increment a count given as arg (either no value or value parsed as boolean)
       if (checkAllAliases(key, flags.counts) && (isUndefined(value) || typeof value === 'boolean')) {
-        value = increment()
+        value = incrementMarker
       }
 
       // Set normalized value when key is in 'normalize' and in 'arrays'
@@ -850,7 +850,7 @@ export class YargsParser {
         }
       }
 
-      if (value === increment()) {
+      if (value === incrementMarker) {
         o[key] = increment(o[key])
       } else if (Array.isArray(o[key])) {
         if (duplicate && isTypeArray && isValueArray) {
@@ -1098,6 +1098,11 @@ function combineAliases (aliases: Dictionary<string | string[]>): Dictionary<str
   return combined
 }
 
+// A count argument carries no value of its own: it is replaced by this marker
+// so that `setKey` can tell "increment the count" apart from a real value, and
+// a literal `1` passed to a non-count option is not mistaken for a count.
+const incrementMarker = Symbol('increment')
+
 // this function should only be called when a count is given as an arg
 // it is NOT called to set a default value
 // thus we can start the count at 1 instead of 0
diff --git a/test/yargs-parser.mjs b/test/yargs-parser.mjs
index 4c692375..953c8a98 100644
--- a/test/yargs-parser.mjs
+++ b/test/yargs-parser.mjs
@@ -1658,6 +1658,20 @@ describe('yargs-parser', function () {
 
       argv.error.message.should.equal('Invalid configuration: counter, opts.count excludes opts.narg.')
     })
+
+    // See: https://github.com/yargs/yargs-parser/issues/506
+    it('should not increment an option that is not a counter when its value is 1', function () {
+      parser('-x 3 -x 1').x.should.deep.equal([3, 1])
+      parser('-x 1 -x 3').x.should.deep.equal([1, 3])
+      parser('--foo 2 --foo 1').foo.should.deep.equal([2, 1])
+    })
+
+    it('should not increment a non-counter with value 1 when duplicate-arguments-array is false', function () {
+      const parsed = parser('-x 3 -x 1', {
+        configuration: { 'duplicate-arguments-array': false }
+      })
+      parsed.x.should.equal(1)
+    })
   })
 
   describe('array', function () {