diff --git a/hera_pspec/pspecdata.py b/hera_pspec/pspecdata.py
index afb50769..bb28fbd5 100644
--- a/hera_pspec/pspecdata.py
+++ b/hera_pspec/pspecdata.py
@@ -66,7 +66,7 @@ def __init__(self, dsets=[], wgts=[], dsets_std=None, labels=None, beam=None):
 
         # Store the input UVData objects if specified
         if len(dsets) > 0:
-            self.add(dsets, wgts,dsets_std=dsets_std, labels=labels)
+            self.add(dsets, wgts, dsets_std=dsets_std, labels=labels)
 
         # Store a primary beam
         self.primary_beam = beam
@@ -96,7 +96,6 @@ def add(self, dsets, wgts, labels=None, dsets_std=None):
             standard deviations (real and imaginary) of data to add to the
             collection. If dsets is a dict, will assume dsets_std is a dict
             and if dsets is a list, will assume dsets_std is a list.
-
         """
         # Check for dicts and unpack into an ordered list if found
         if isinstance(dsets, dict):
@@ -119,7 +118,6 @@ def add(self, dsets, wgts, labels=None, dsets_std=None):
                 _dsets_std = [dsets_std[key] for key in labels]
                 dsets_std = _dsets_std
 
-
             # Unpack dsets and wgts dicts
             labels = dsets.keys()
             _dsets = [dsets[key] for key in labels]
@@ -144,7 +142,6 @@ def add(self, dsets, wgts, labels=None, dsets_std=None):
             raise TypeError("dsets, dsets_std, and wgts must be UVData"
                             "or lists of UVData")
 
-
         # Make sure enough weights were specified
         assert(len(dsets) == len(wgts))
         assert(len(dsets_std) == len(dsets))
@@ -161,16 +158,28 @@ def add(self, dsets, wgts, labels=None, dsets_std=None):
                 raise TypeError("Only UVData objects (or None) can be used as "
                                 "error sets")
 
+        # Store labels (if they were set)
+        if self.labels is None:
+            self.labels = []
+        if labels is None:
+            labels = ["dset{:d}".format(i) for i in range(len(self.dsets), len(dsets)+len(self.dsets))]
+        self.labels += labels
+
         # Append to list
         self.dsets += dsets
         self.wgts += wgts
         self.dsets_std += dsets_std
 
-        # Store labels (if they were set)
-        if labels is None:
-            self.labels = [None for d in dsets]
-        else:
-            self.labels += labels
+        # Check for repeated labels, and make them unique
+        for i, l in enumerate(self.labels):
+            ext = 1
+            while True:
+                if l in self.labels[:i]:
+                    l = self.labels[i] + "_{:d}".format(ext)
+                    ext += 1
+                else:
+                    self.labels[i] = l
+                    break
 
         # Store no. frequencies and no. times
         self.Nfreqs = self.dsets[0].Nfreqs
@@ -2611,9 +2620,6 @@ def pspec_run(dsets, filename, dsets_std=None, groupname=None, dset_labels=None,
 
     if dset_labels is None:
         dset_labels = ["dset{}".format(i) for i in range(Ndsets)]
-    else:
-        # enforce unique dset labels
-        assert len(set(dset_labels)) == len(dset_labels), "Found repeated dest labels: each one must be unique"
 
     # load data if fed as filepaths
     if isinstance(dsets[0], (str, np.str)):
diff --git a/hera_pspec/tests/test_pspecdata.py b/hera_pspec/tests/test_pspecdata.py
index 67427a98..13d047b2 100644
--- a/hera_pspec/tests/test_pspecdata.py
+++ b/hera_pspec/tests/test_pspecdata.py
@@ -159,6 +159,18 @@ def test_init(self):
         key = (0, (24, 25), 'xx')
         nt.assert_true(np.all(np.isclose(ds.x(key), ds.w(key))))
 
+        # Test labels when adding dsets
+        uvd = self.uvd
+        ds = pspecdata.PSpecData()
+        nt.assert_equal(len(ds.labels), 0)
+        ds.add([uvd, uvd], [None, None])
+        nt.assert_equal(len(ds.labels), 2)
+        ds.add(uvd, None, labels='foo')
+        nt.assert_equal(len(ds.dsets), len(ds.labels), 3)
+        nt.assert_equal(ds.labels, ['dset0', 'dset1', 'foo'])
+        ds.add(uvd, None)
+        nt.assert_equal(ds.labels, ['dset0', 'dset1', 'foo', 'dset3'])
+
         # Test some exceptions
         ds = pspecdata.PSpecData()
         nt.assert_raises(ValueError, ds.get_G, key, key)
@@ -1312,7 +1324,6 @@ def test_pspec_run():
     nt.assert_raises(AssertionError, pspecdata.pspec_run, fnames, "./out.hdf5", blpairs=(1, 2), verbose=False)
     nt.assert_raises(AssertionError, pspecdata.pspec_run, fnames, "./out.hdf5", blpairs=[1, 2], verbose=False)
     nt.assert_raises(AssertionError, pspecdata.pspec_run, fnames, "./out.hdf5", beam=1, verbose=False)
-    nt.assert_raises(AssertionError, pspecdata.pspec_run, fnames, "./out.hdf5", dset_labels=['hi', 'hi'], verbose=False)
 
     if os.path.exists("./out.hdf5"):
         os.remove("./out.hdf5")
diff --git a/hera_pspec/uvpspec.py b/hera_pspec/uvpspec.py
index f1c77b61..c6b10ccd 100644
--- a/hera_pspec/uvpspec.py
+++ b/hera_pspec/uvpspec.py
@@ -1535,14 +1535,12 @@ def combine_uvpspec(uvps, verbose=True):
         u.freq_array.extend(spw_freqs)
         u.dly_array.extend(spw_dlys)
 
-    
     # Convert to numpy arrays    
     u.spw_array = np.array(u.spw_array)
     u.freq_array = np.array(u.freq_array)
     u.dly_array = np.array(u.dly_array)
     u.pol_array = np.array(new_pols)
 
-    
     # Number of spectral windows, delays etc.
     u.Nspws = Nspws
     u.Nblpairts = Nblpairts