diff --git a/numpy/_core/src/multiarray/convert_datatype.c b/numpy/_core/src/multiarray/convert_datatype.c
index 7de76ac63ed6..59b6298b5815 100644
--- a/numpy/_core/src/multiarray/convert_datatype.c
+++ b/numpy/_core/src/multiarray/convert_datatype.c
@@ -1597,13 +1597,12 @@ PyArray_ResultType(
         return NULL;
     }
 
-    PyArray_DTypeMeta **all_DTypes = (PyArray_DTypeMeta **)workspace;
+    PyArray_DTypeMeta **all_DTypes = (PyArray_DTypeMeta **)workspace; // borrowed references
     PyArray_Descr **all_descriptors = (PyArray_Descr **)(&all_DTypes[narrs+ndtypes]);
 
     /* Copy all dtypes into a single array defining non-value-based behaviour */
     for (npy_intp i=0; i < ndtypes; i++) {
         all_DTypes[i] = NPY_DTYPE(descrs[i]);
-        Py_INCREF(all_DTypes[i]);
         all_descriptors[i] = descrs[i];
     }
 
@@ -1628,14 +1627,10 @@ PyArray_ResultType(
             all_descriptors[i_all] = PyArray_DTYPE(arrs[i]);
             all_DTypes[i_all] = NPY_DTYPE(all_descriptors[i_all]);
         }
-        Py_INCREF(all_DTypes[i_all]);
     }
 
     PyArray_DTypeMeta *common_dtype = PyArray_PromoteDTypeSequence(
             narrs+ndtypes, all_DTypes);
-    for (npy_intp i=0; i < narrs+ndtypes; i++) {
-        Py_DECREF(all_DTypes[i]);
-    }
     if (common_dtype == NULL) {
         goto error;
     }
diff --git a/numpy/_core/src/multiarray/multiarraymodule.c b/numpy/_core/src/multiarray/multiarraymodule.c
index e74e14bf10c2..cddfad16a972 100644
--- a/numpy/_core/src/multiarray/multiarraymodule.c
+++ b/numpy/_core/src/multiarray/multiarraymodule.c
@@ -3583,24 +3583,28 @@ static PyObject *
 array_result_type(PyObject *NPY_UNUSED(dummy), PyObject *const *args, Py_ssize_t len)
 {
     npy_intp i, narr = 0, ndtypes = 0;
-    PyArrayObject **arr = NULL;
-    PyArray_Descr **dtypes = NULL;
     PyObject *ret = NULL;
 
     if (len == 0) {
         PyErr_SetString(PyExc_ValueError,
                         "at least one array or dtype is required");
-        goto finish;
+        return NULL;
     }
 
-    arr = PyArray_malloc(2 * len * sizeof(void *));
+    NPY_ALLOC_WORKSPACE(arr, PyArrayObject *, 2 * 3, 2 * len);
     if (arr == NULL) {
-        return PyErr_NoMemory();
+        return NULL;
     }
-    dtypes = (PyArray_Descr**)&arr[len];
+    PyArray_Descr **dtypes = (PyArray_Descr**)&arr[len];
+
+    PyObject *previous_obj = NULL;
 
     for (i = 0; i < len; ++i) {
         PyObject *obj = args[i];
+        if (obj == previous_obj) {
+            continue;
+        }
+
         if (PyArray_Check(obj)) {
             Py_INCREF(obj);
             arr[narr] = (PyArrayObject *)obj;
@@ -3636,7 +3640,7 @@ array_result_type(PyObject *NPY_UNUSED(dummy), PyObject *const *args, Py_ssize_t
     for (i = 0; i < ndtypes; ++i) {
         Py_DECREF(dtypes[i]);
     }
-    PyArray_free(arr);
+    npy_free_workspace(arr);
     return ret;
 }